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Medical Dictionary


fetoplacental (fe′to-pla-sen′tal)
Relating to the fetus and its placenta.

fetoproteins (fe-to-pro′tenz)
Fetal proteins found in small amounts in adults in the following forms: α-f. (AFP) increases in maternal blood during pregnancy and, when detected by amniocentesis, is an important indicator of open neural tube defects and is also used as a tumor marker in adults (see definition below); β-f., although a fetal liver protein, has been detected in adult patients with liver disease; γ-f. occurs in various neoplasms. SEE ALSO: fetoglobulins. α fetoprotein a protein normally produced during the 12th to 15th week of gestation, decreasing thereafter, but appearing in the blood in certain tumors, such as embryonal carcinomas of the testis and ovary, hepatoma, and less often in patients with carcinomas of the pancreas, stomach, colon, or lung. When present, a useful marker in following the course of a tumor.

fetor (fe′tor)
A very offensive odor. [L. an offensive smell, fr. feteo, to stink] f. hepaticus a peculiar odor to the breath in persons with severe liver disease; caused by volatile aromatic substances that accumulate in the blood and urine due to defective hepatic metabolism. SYN: liver breath. f. oris SYN: halitosis.

fetoscope (fe′to-skop)
1. A fiberoptic endoscope used in fetology. 2. A stethoscope designed for listening to fetal heart sounds.

fetoscopy (fe-tos′ko-pe)
Use of a fiberoptic endoscope to view the fetus and the fetal surface of the placenta transabdominally, and also for collection of fetal blood from the umbilical vein for antenatal diagnosis of fetal disorders.

fetuin (fe-too′in)
A low molecular-weight globulin that constitutes nearly the total globulin in fetal blood. [fetus + -in]

fetus, pl .fetuses (fe′tus, fe′tus-ez)
1. The unborn young of a viviparous animal following the embryonic period. 2. [NA] In humans, the product of conception from the end of the eighth week to the moment of birth. [L. offspring] f. in fetu condition in which a small, imperfectly formed f. is contained within a f.. harlequin f. a severe autosomal recessive form of collodion baby in a newborn, usually premature, infant; i.e., a form of ichthyosiform erythroderma characterized by encasement of the body in grayish brown, often fissured plaques resembling plates of armor and by grotesque deformity of the face with eclabium and gangrene of terminal phalanges; usually fatal within a few days, although treatment with 13-cis-retinoic acid has been successful in some cases. SYN: ichthyosis fetalis (1) . impacted f. a f. which, because of its large size or narrowing of the pelvic canal, has become wedged and incapable of spontaneous advance or recession. f. papyraceus one of twin fetuses that has died and been pressed flat against the uterine wall by the growth of the living f.. f. sanguinolentis (san-gwi′no-len′tis) dead f. that has become macerated.

Robert, German nucleic acid biochemist and cytochemist, 1884–1955. First to detect DNA in cells by a specific cytochemical test. See F. cytometry.

Abbreviation for forced expiratory volume, with subscript indicating time interval in seconds.

fever (fe′ver)
A complex physiologic response to disease mediated by pyrogenic cytokines and characterized by a rise in core temperature, generation of acute phase reactants, and activation of immune systems. SYN: febris, pyrexia. [A.S. fefer] absorption f. an elevation of temperature often occurring, without other untoward symptoms, shortly after childbirth, assumed to be due to absorption of uterine discharges through abrasions of the vaginal wall. acclimating f. elevated temperature with malaise that occurs upon working in a very hot environment. Aden f. SYN: dengue. aestivoautumnal f. SYN: falciparum malaria. African hemorrhagic f. hemorrhagic f. associated with the morphologically similar but antigenically distinct Marburg and Ebola viruses as well as numerous other viruses that cause similar diseases. SEE ALSO: viral hemorrhagic f.. African tick f. SYN: Crimean-Congo hemorrhagic f.. African tick-bite f. a febrile disease caused by the bacterium Rickettsia africae in southern Africa and characterized by taches noires at the sites of bites by infected Amblyomma ticks and lymphadenopathy. algid pernicious f. a pernicious malarial attack in which the patient presents symptoms of collapse and shock. ardent f. a term sometimes applied to hyperpyrexia occurring in intermittent malarial f.. SYN: heat apoplexy (2) . Argentinean hemorrhagic f. a form of hemorrhagic f. observed in South America, seemingly transmitted by contact from rodents to humans and caused by the Junin virus, a member of the family Arenaviridae. artificial f. SYN: pyretotherapy. aseptic f. f. accompanied by malaise due to absorption of dead but not infected tissue following an injury. Assam f. SYN: visceral leishmaniasis. Australian Q f. a variety of Q f. occurring in Australia; an acute infectious rickettsial infection caused by Coxiella burnetii and transmitted by ticks, enzootic in animals in Australia, especially bandicoots. autumn f. 1. a f. resembling dengue occurring at the end of the summer in India; SYN: seven-day f. (1) . 2. SYN: hasamiyami. benign tertian f. SYN: vivax malaria. bilious remittent f. 1. old term for relapsing f.; 2. malarial “bilious” vomiting associated with marked increase of serum bilirubin. black f. SYN: Rocky Mountain spotted f.. blackwater f. hemoglobinuria resulting from severe hemolysis occurring in falciparum malaria. SYN: malarial hemoglobinuria. blue f. SYN: Rocky Mountain spotted f.. Bolivian hemorrhagic f. a disease similar to Argentinian hemorrhagic f. but caused by the Machupo virus, a member of the family Arenaviridae. bouquet f. SYN: dengue. boutonneuse f. SYN: Mediterranean spotted f.. brass founder's f. an occupational disease, characterized by malaria-like symptoms, due to inhalation of particles and fumes of metallic oxides. Fumes are formed by evaporation at very high temperature and condensation in air into fine particles. SYN: brass founder's ague, foundryman's f., metal fume f., zinc fume f.. Brazilian hemorrhagic f. SYN: Brazilian spotted f.. Brazilian purpuric f. SYN: Brazilian spotted f.. Brazilian spotted f. fulminating sepsis, usually beginning with conjunctivitis, characterized by purpuric skin lesions, a high fatality rate; thought to be due to Haemophilus aegyptius. SYN: Brazilian hemorrhagic f., Brazilian purpuric f.. breakbone f. SYN: dengue. Bunyamwera f. a febrile illness of humans in Africa caused by the Bunyamwera virus (family Bunyaviridae) and transmitted by culicine mosquitoes. Burdwan f. SYN: visceral leishmaniasis. Bwamba f. a febrile illness of humans in Africa caused by a virus of the family Bunyaviridae and transmitted by mosquitoes. cachectic f. SYN: visceral leishmaniasis. camp f. 1. any epidemic febrile illness affecting troops in an encampment; 2. obsolete term for typhus. canicola f. a disease of humans caused by the canicola serovar of Leptospira interrogans and transmitted by infective urine, usually from dogs but rarely from cattle and swine. catarrhal f. old term for the group of respiratory tract diseases including the common cold, influenza, and lobular and lobar pneumonia. cat-bite f. SYN: cat-bite disease. catheter f. SYN: urinary f.. catscratch f. SYN: catscratch disease. Central European tick-borne f. SYN: tick-borne encephalitis (Central European subtype). cerebrospinal f. SYN: meningococcal meningitis. Charcot intermittent f. f., chills, right upper quadrant pain, and jaundice associated with intermittently obstructing common duct stones. childbed f. SYN: puerperal f.. Colorado tick f. an infection caused by Colorado tick f. virus and transmitted to humans by Dermacentor andersoni; the symptoms are mild, there is no rash, the temperature is not excessive, and the disease is rarely, if ever, fatal. Congolian red f. SYN: murine typhus. continued f. obsolete term for a continual febrile illness without intermittency as with malaria. Many cases were typhoid f., but included many types of febrile illnesses. cotton-mill f. SYN: byssinosis. Crimean f. SYN: Mediterranean spotted f.. Crimean-Congo hemorrhagic f. a form of hemorrhagic f. distinct from Omsk hemorrhagic f., occurring in central Russia, transmitted by species of the tick Hyalomma, and caused by Crimean-Congo hemorrhagic f. virus, a member of the Bunyaviridae family; horses are the chief reservoir of human infection; characterized by abrupt onset, high f., headache, myalgia, widespread petechial hemorrhagic lesions, gastrointestinal bleeding, high fatality rate. SYN: African tick f.. dandy f. SYN: dengue. date f. SYN: dengue. deer-fly f. SYN: tularemia. dehydration f. SYN: thirst f.. dengue f. SYN: dengue. dengue hemorrhagic f. SYN: dengue. desert f. SYN: primary coccidioidomycosis. digestive f. a slight rise of body temperature occurring during the period of digestion. diphasic milk f. SYN: tick-borne encephalitis (Central European subtype). double quotidian f. malaria in which two paroxysms of f. occur daily. drug f. f. resulting from an allergic reaction to a drug that clears rapidly on discontinuation of the drug. Dumdum f. SYN: visceral leishmaniasis. Dutton relapsing f. SYN: Dutton disease. Ebola hemorrhagic f. SYN: hemorrhagic f.. elephantoid f. lymphangitis and an elevation of temperature marking the beginning of endemic elephantiasis (filariasis). enteric f. 1. SYN: typhoid f.. 2. the group of typhoid and paratyphoid fevers. entericoid f. a f., neither paratyphoid nor typhoid, resembling the latter. ephemeral f. a febrile episode lasting no more than a day or two. epidemic hemorrhagic f. a condition characterized by acute onset of headache, chills and high f., sweating, thirst, photophobia, coryza, cough, myalgia, arthralgia, and abdominal pain with nausea and vomiting; this phase lasts from 3–6 days and is followed by capillary and renal interstitial hemorrhages, edema, oliguria, azotemia, and shock; most varieties are caused by numerous viruses including togaviruses, arenaviruses, flaviviruses, and bunyaviruses, and are rodent-borne. SYN: hemorrhagic f. with renal syndrome, Songo f.. epimastical f. a f. increasing steadily until its acme is reached, then declining by crisis or lysis. eruptive f. SYN: Mediterranean spotted f.. essential f. f. without known infectious disease. exanthematous f. f. associated with an exanthem. exsiccation f. SYN: thirst f.. falciparum f. SYN: falciparum malaria. familial Mediterranean f. SYN: familial paroxysmal polyserositis. Far East hemorrhagic f. tick-borne infection with Rickettsia sibirica, seen primarily in Siberia and Mongolia. fatigue f. an elevation of the body temperature, lasting sometimes several days, following excessive and long continued muscular exertion. field f. a leptospirosis caused by leptospira. five-day f. SYN: trench f.. Flinders Island spotted f. a febrile disease caused by the bacterium Rickettsia honei in southeastern Australia and characterized by headache, myalgia, and maculopapular rash. [named after Flinders Island in Tasmania, Australia, from which the first cases of the disease were identified] flood f. SYN: tsutsugamushi disease. food f. a disorder seen primarily in childhood, consisting of a sudden rise of temperature accompanied by marked digestive disturbances, which lasts from a few days to several weeks; believed to be a form of food poisoning. Fort Bragg f. SYN: pretibial f.. foundryman's f. SYN: brass founder's f.. Gambian f. an irregular relapsing f., lasting 1–4 days with intermissions of 2–5 days, marked by enlargement of the spleen, rapid pulse, and breathing; due to the presence in the blood of Trypanosoma brucei gambiense, the pathogenic microorganism of Gambian or West African sleeping sickness. glandular f. SYN: infectious mononucleosis. Haverhill f. an infection by Streptobacillus moniliformis marked by initial chills and high f. (gradually subsiding), by arthritis usually in the larger joints and spine, and by a rash occurring chiefly over the joints and on the extensor surfaces of the extremities; “Haverhill f.” is used to indicate Streptobacillus moniliformis infections not associated with rat bite but resulting from contaminated food or water. SYN: erythema arthriticum epidemicum. [Haverhill, MA, where an epidemic occurred in 1926] hay f. a form of atopy characterized by an acute irritative inflammation of the mucous membranes of the eyes and upper respiratory passages accompanied by itching and profuse watery secretion, usually without temperature elevation, followed occasionally by bronchitis and asthma; the episode recurs annually at the same or nearly the same time of the year, in spring, summer, or late summer and autumn, caused by an allergic reaction to the pollen of trees, grasses, weeds, flowers, etc. SYN: allergic coryza. hematuric bilious f. hematuria due to renal lesions caused by the malarial hematozoon, Plasmodium falciparum. hemoglobinuric f. SYN: malarial hemoglobinuria. hemorrhagic f. a syndrome that occurs in perhaps 20–40% of infections by a number of different viruses of the families Arenaviridae (Lassa f., Bolivian hemorrhagic f., Argentinean hemorrhagic f.), Bunyaviridae (Crimean-Congo hemorrhagic f.), Flaviviridae (Dengue hemorrhagic f., Omsk hemorrhagic f.), Filoviridae (Ebola f., Marburg virus disease), etc. Some types of hemorrhagic f. are tick-borne, others mosquito-borne, and some seem to be zoonoses; clinical manifestations are high f., scattered petechiae, gastrointestinal tract and other organ bleeding, hypotension, and shock; kidney damage may be severe, especially in Korean hemorrhagic f. and neurologic signs may appear, especially in the Argentinean-Bolivian types. Five types of hemorrhagic f. are transmissible person-to-person: Bolivian hemorrhagic f., Lassa f., Ebola f., Marburg virus disease, and Crimean-Congo hemorrhagic f.. SEE ALSO: epidemic hemorrhagic f.. SYN: Ebola hemorrhagic f.. hemorrhagic f. with renal syndrome SYN: epidemic hemorrhagic f.. hepatic intermittent f. ague-like paroxysms of f. occurring in cases of one or more stones in the common bile duct. herpetic f. a disease of short duration, apparently infectious, marked by chills, nausea, elevation of temperature, sore throat, and a herpetic eruption on the face and other areas; primary infection is with herpes simplex virus. hospital f. SYN: epidemic typhus. icterohemorrhagic f. infection with the variety of Leptospira interrogans serotype known as icterohemorrhagiae, characterized by f., jaundice, hemorrhagic lesions, azotemia, and central nervous system manifestations. SYN: leptospirosis icterohemorrhagica. Ilhéus f. a febrile illness caused by the Ilhéus virus, a Flavivirus, and transmitted by a mosquito. SEE ALSO: Ilhéus encephalitis. inanition f. SYN: thirst f.. induced f. SYN: pyretotherapy. intermittent malarial f. intermittent malaria. inundation f. SYN: tsutsugamushi disease. island f. SYN: tsutsugamushi disease. jail f. SYN: typhus. Japanese river f. SYN: tsutsugamushi disease. Japanese spotted f. a febrile disease caused by the bacterium Rickettsia japonica and characterized by headache and exanthema; found in Japan. jungle f. SYN: malaria. jungle yellow f. a form occurring in South America, transmitted by Aedes leucocelaenus and various treetop mosquitoes of the Haemagogus complex; transmitted normally to primates, occasionally by chance to humans to set off a human outbreak of classical yellow f. transmitted by Aedes aegypti. Katayama f. SYN: Katayama disease. kedani f. SYN: tsutsugamushi disease. Kenya f. SYN: Mediterranean spotted f.. Kew Gardens f. SYN: rickettsialpox. [Kew Gardens, area in Queens, NYC, where first reported] Kinkiang f. SYN: schistosomiasis japonica. Korean hemorrhagic f. a form of epidemic hemorrhagic f. caused by the Hantaan virus. SYN: Manchurian hemorrhagic f.. Lassa f. a severe form of epidemic hemorrhagic f. which is highly fatal. It was first recognized in Lassa, Nigeria, is caused by the Lassa virus, a member of the Arenaviridae family, and is characterized by high f., sore throat, severe muscle aches, skin rash with hemorrhages, headache, abdominal pain, vomiting, and diarrhea; the multimammate rat Mastomys natalensis serves as reservoir, but person-to-person transmission also is common. SYN: Lassa hemorrhagic f.. Lassa hemorrhagic f. SYN: Lassa f.. laurel f. an affection of the same nature as hay f., occurring at the time of flowering of laurel. malarial f. malaria. malignant tertian f. SYN: falciparum malaria. Malta f. SYN: brucellosis. Manchurian f. a f. closely resembling typhus that prevails from September to December in South Manchuria; the probable pathogen is Rickettsia manchuriae. Manchurian hemorrhagic f. SYN: Korean hemorrhagic f.. Marseilles f. SYN: Mediterranean spotted f.. marsh f. SYN: malaria. Mediterranean f. 1. SYN: brucellosis. 2. SYN: familial paroxysmal polyserositis. Mediterranean erythematous f. a form of Mediterranean spotted f. that causes skin redness; its course and other symptoms may be similar to those of Mediterranean exanthematous f.. See Rickettsia conorii. Mediterranean exanthematous f. See boutonneuse f.. Mediterranean spotted f. tick-borne infection with Rickettsia conorii seen in Africa, Europe, the Middle East, and India and known by different names in different areas, e.g., Marseilles f., Crimean f., Indian tick typhus, and Kenya f.. Two forms are Mediterranean exanthematous f. (q.v.), which manifests as skin eruptions, and Mediterranean erythematous f. (q.v.), which manifests as skin redness. See Rickettsia conorii. SYN: boutonneuse f., Crimean f., eruptive f., fièvre boutonneuse, Indian tick typhus, Kenya f., Marseilles f., tick typhus. meningotyphoid f. typhoid f. marked by symptoms of irritation or inflammation of the cerebral or spinal meninges. metal fume f. SYN: brass founder's f.. Mexican spotted f. SYN: Rocky Mountain spotted f.. miliary f. 1. an infectious disease characterized by profuse sweating and the production of sudamina, occurring formerly in severe epidemics; 2. SYN: miliaria. milk f. 1. a slight elevation of temperature following childbirth, said to be due to the establishment of the secretion of milk, but probably the same as absorption f.; 2. an afebrile metabolic disease, occurring shortly after parturition in dairy cattle, characterized by hypocalcemia and manifested by loss of consciousness and general paralysis. mill f. SYN: byssinosis. miniature scarlet f. a reaction consisting of f., nausea, vomiting, and a transient scarlatiniform rash that appears in a susceptible person when injected with the toxin of Streptococcus pyogenes. [L. minio, pp. atus, to color with minium, red-lead] monoleptic f. a continued f. having but one paroxysm. Cf.:polyleptic f.. Mossman f. a f., noted especially among sugar-cane cutters in the Mossman District of North Queensland, caused by a leptospira. mud f. a leptospirosis caused by the grippotyphosa serovar of Leptospira interrogans; mumu f. samoan term for elephantoid f.. nanukayami f. a form of leptospirosis known in Japan and caused by a leptospira normally found in the field mouse or vole. SYN: nanukayami. nine mile f. SYN: Q f.. nodal f. SYN: erythema nodosum. North Queensland tick f. a mild form of tick-borne typhus with eschar, adenopathy, rash, and f., caused by Rickettsia australis and thought to be transmitted by the tick, Ixodes holocyclus. Omsk hemorrhagic f. a form of epidemic hemorrhagic f. found in central Russia, caused by the Omsk hemorrhagic f. virus, a member of the family Flaviviridae, and transmitted by Dermacentor ticks; associated with gastrointestinal symptoms and hemorrhages but little or no central nervous system involvement. o'nyong-nyong f. a denguelike disease caused by the o'nyong-nyong virus, a member of the family Togaviridae, and transmitted by a mosquito, characterized by joint pains and notable lymphadenopathy followed by a maculopapular eruption of the face which extends to the trunk and extremities but fades in several days without desquamation. Oropouche f. acute febrile illness caused by a species of Bunyavirus. Oroya f. a generalized, acute, febrile, endemic, and systemic form of bartonellosis; marked by high f., rheumatic pains, progressive, severe anemia, and albuminuria. SYN: Carrión disease. Pahvant Valley f. SYN: tularemia. paludal f. SYN: malaria. pappataci f. SYN: phlebotomus f.. paratyphoid f. an acute infectious disease with symptoms and lesions resembling those of typhoid f., though milder in character; associated with the presence of the paratyphoid organism of which at least three varieties (types A, B, and C) have been described. SYN: paratyphoid. parenteric f. one of a group of fevers clinically resembling typhoid and paratyphoid A and B, but caused by bacteria differing specifically from those of either of these diseases. parrot f. SYN: psittacosis. Pel-Ebstein f. the remittent f. common in Hodgkin disease. SYN: Pel-Ebstein disease. periodic f. an obsolete term introduced to describe the intermittent febrile episodes seen in disease later recognized and named familial Mediterranean f.. Persian relapsing f. a tick-borne relapsing f., occurring in the Middle East, caused by Borrelia persica and transmitted by Ornithodoros tholozani and possibly by Ornithodoros lahorensis. pharyngoconjunctival f. a disease usually occurring in epidemic form characterized by f., pharyngitis, and conjunctivitis, and caused by several types of adenoviruses. Philippine hemorrhagic f. severe arbovirus infection with hemorrhagic manifestations, considerable mortality, probably due to mosquito borne dengue virus; seen in tropical and subtropical urban areas of southeast Asia, South Pacific, Australia, Central and South America, and the Caribbean islands. phlebotomus f. an infectious but not contagious disease occurring in the Balkan Peninsula and other parts of southern Europe, caused by several viruses in the family Bunyaviridae apparently introduced by the bite of the sandfly, Phlebotomus papatasii; symptoms resemble those of dengue but are less severe and of shorter duration. SYN: dog disease, pappataci f., Pym f., sandfly f., three-day f.. pinta f. a term used in Mexico for Rocky Mountain spotted f.. polka f. SYN: dengue. polyleptic f. a f. occurring in two or more paroxysms; e.g., smallpox, relapsing f., intermittent f.. Cf.:monoleptic f.. polymer fume f. an occupational disease marked by f., pain in the chest, and cough caused by the inhalation of fumes given off by a plastic, polytetrafluorethylene, when heated. pretibial f. a mild disease first observed among military personnel at Fort Bragg, North Carolina, characterized by f., moderate prostration, splenomegaly, and a rash on the anterior aspects of the legs; due to the autumnalis serovar of Leptospira interrogans. SYN: Fort Bragg f.. protein f. f. produced by the injection of foreign protein, such as milk. puerperal f. postpartum sepsis with a rise in f. after the first 24 hours following delivery, but before the eleventh postpartum day. SYN: childbed f., puerperal sepsis. Pym f. SYN: phlebotomus f.. pyogenic f. SYN: pyemia. Q f. a disease caused by the rickettsia Coxiella burnetii, which is propagated in sheep and cattle, where it produces no symptoms; human infections occur as a result of contact not only with such animals but also with other infected humans, air and dust, wild reservoir hosts, and other sources. SYN: nine mile f.. [Q, for “query,” so named because etiologic agent was unknown] quartan f. SYN: malariae malaria. quintan f. SYN: trench f.. quotidian f. SYN: quotidian malaria. rabbit f. SYN: tularemia. rat-bite f. a single designation for two bacterial diseases associated with rat bites, one caused by Streptobacillus moniliformis ( e.g., Haverhill f.), the other by Spirillum minus ( e.g., sodoku); both diseases are characterized by relapsing f., chills, headache, arthralgia, lymphadenopathy, and a maculopapular rash on the extremities. SYN: rat-bite disease, sodoku, sokosho. recrudescent typhus f. SYN: Brill-Zinsser disease. recurrent f. SYN: relapsing f.. red f., red f. of the Congo SYN: murine typhus. relapsing f. an acute infectious disease caused by any one of a number of strains of Borrelia, marked by a number of febrile attacks lasting about 6 days and separated from each other by apyretic intervals of about the same length; the microorganism is found in the blood during the febrile periods but not during the intervals, the disappearance being associated with specific antibodies and previously evoked antibodies. There are two epidemiologic varieties: 1) the louse-borne variety, occurring chiefly in Europe, northern Africa, and India, and caused by strains of B. recurrentis; 2) the tick-borne variety, occurring in Africa, Asia, and North and South America, caused by various species of Borrelia, each of which is transmitted by a different species of the soft tick, Ornithodoros. SYN: bilious typhoid of Griesinger, recurrent f., spirillum f., typhinia. remittent f. a f. pattern in which temperature varies during each 24 hour period, but never reaches normal. Most fevers are remittent and the pattern is not characteristic of any disease, although in the 19th century it was considered a diagnostic term. remittent malarial f. remittent malaria. rheumatic f. a subacute febrile syndrome occurring after group A β-hemolytic streptococcal infection (usually pharyngitis) and mediated by an immune response to the organism; most often seen in children and young adults; features include f., myocarditis (causing tachycardia and sometimes acute cardiac failure), endocarditis (with valvular incompetence, followed after healing by scarring), and migratory polyarthritis; less often, subcutaneous nodules, erythema marginatum, and Syndenham chorea; relapses can occur after reinfection with streptococci.Criteria for diagnosis of acute rheumatic f. were published by Jones in 1944. Regimens for prevention of initial and recurring attacks, and guidelines for treatment, have remained essentially unchanged for decades. Although acute rheumatic f. has ceased to be a major public health problem in the U.S., the incidence is still high in developing countries. In India, for example, where medical services have failed to keep pace with urbanization and industrialization, 250,000 new cases are diagnosed in school children annually. The incidence of rheumatic f. in the U.S., which had declined steadily for several decades after antibiotic treatment of streptococcal pharyngitis (strep throat) became standard, began rising again in the late 1980s and 1990s, with some urban clusters showing a 10-fold increase in incidence. Historically, rheumatic f. is a disease of children in lower socioeconomic strata. In a number of recent clusters, most of the victims were adults, and when children have been involved, they have often belonged to middle- and upper-class families. As many as 75% of patients denied any history of recent sore throat, and some of those who had been diagnosed with preceding strep throat had been treated with antibiotics. Cardiac and articular manifestations of rheumatic f. are considered autoimmune phenomena, due to a postulated rheumatogenic factor that has never been isolated. Pathogenicity in streptococci is known to be associated with the presence of an M protein in the cell membrane, which is also responsible for the appearance of a surface fuzz on microscopic examination of organisms, and the production of mucoid colonies on blood agar. Organisms implicated in several recent clusters of rheumatic f. have belonged to mucoid strains, particularly serotypes M 3 and M 18. Widespread antibiotic use in recent years, not all of it appropriate or justified by current medical knowledge, may have led to the resurgence of rheumatic f. by favoring the rise and spread of virulent strains of streptococcus, or by reducing the ability of certain populations to mount an immune response against them. Infectious disease authorities are currently reevaluating the diagnosis and management of streptococcal infection, particularly with respect to rapid slide tests and to drug regimens approved for use in the treatment of acute streptococcal pharyngitis and hence in the prophylaxis of rheumatic f.. See Jones criteria, under criterion. rice-field f. a febrile illness affecting workers in rice fields, reported in Po valley in Italy and in Sumatra, caused by infection with a species of Leptospira. Rift Valley f. a fatal endemic disease of sheep, caused by Rift Valley f. virus, a member of the family Bunyaviridae, which is also pathogenic for humans and cattle, producing in humans f. of an undifferentiated type; transmitted by mosquitoes and direct contact. [Rift Valley in Kenya] Rocky Mountain spotted f. an acute infectious disease of high mortality, characterized by frontal and occipital headache, intense lumbar pain, malaise, a moderately high continuous f., and a rash on wrists, palms, ankles, and soles from the second to the fifth day, later spreading to all parts of the body; it occurs in the spring of the year primarily in the southeastern U.S. and the Rocky Mountain region, although it is also endemic elsewhere in the U.S., in parts of Canada, in Mexico, and in South America; the pathogenic organism is Rickettsia rickettsii, transmitted by two or more tick species of the genus Dermacentor; in the U.S. it is spread by D. andersoni in the western states and D. variabilis (a dog tick) in the eastern states. SYN: black f., black measles (2) , blue disease, blue f., Mexican spotted f., São Paulo f., Tobia f.. Roman f. malignant tertian, falciparum, or aestivoautumnal f., formerly prevalent in the Roman Campagna and in the city of Rome; caused by Plasmodium falciparum. Ross River f. SYN: epidemic polyarthritis. sakushu f. SYN: hasamiyami. Salinem f. infection with Leptospira pyrogenes, reported in Salinem. SYN: Salinem infection. salt f. elevated temperature in an infant, following a rectal injection of a salt solution. SEE ALSO: thirst f.. sandfly f. SYN: phlebotomus f.. San Joaquin f. SYN: primary coccidioidomycosis. San Joaquin Valley f. SYN: primary coccidioidomycosis. São Paulo f. SYN: Rocky Mountain spotted f.. scarlet f. SYN: scarlatina. Schamberg f. SYN: progressive pigmentary dermatosis. Sennetsu f. a disease of humans in western Japan caused by the rickettsia Ehrlichia sennetsu and characterized by f., malaise, anorexia, backache, and lymphadenopathy. septic f. SYN: septicemia. seven-day f. 1. SYN: autumn f. (1) . 2. SYN: hasamiyami. shin bone f. SYN: trench f.. ship f. SYN: typhus. shoddy f. febrile disease occurring in workers in shoddy factories, with cough, dyspnea and headache, caused by inhalation of dust. simian hemorrhagic f. a highly fatal disease of macaque monkeys caused by the simian hemorrhagic f. virus and characterized by f., facial edema, anorexia, adipsia, skin petechiae, diarrhea, hemorrhages, and death. Sindbis f. a febrile illness of humans in Africa, Australia, and other countries, characterized by arthralgia, rash, and malaise; caused by the Sindbis virus, a member of the family Togaviridae, and transmitted by culicine mosquitoes. slime f. leptospiral infection with jaundice, presumably infection by Leptospira icterohemorrhagica. slow f. a continued f. of long duration. smelter's f. metal fume f., occurring in workers in zinc smelters. SYN: smelter's chills, smelter's shakes. snail f. SYN: schistosomiasis. solar f. 1. SYN: dengue. 2. SYN: sunstroke. Songo f. SYN: epidemic hemorrhagic f.. South African tick-bite f. a typhuslike f. of South Africa caused by Rickettsia rickettsii and usually characterized by primary eschar and regional adenitis, rigors, and maculopapular rash on the fifth day, often with severe central nervous system symptoms. spirillum f. SYN: relapsing f.. spotted f. tick typhus caused by Rickettsia rickettsii in North and South America and Siberia. steroid f. f. presumably caused by elevated plasma concentrations of certain pyrogenic steroids; can be produced by administration of etiocholanolone. symptomatic f. SYN: traumatic f.. syphilitic f. the elevation of temperature often present in the early roseolous stage of secondary syphilis. tertian f. SYN: vivax malaria. therapeutic f. SYN: pyrotherapy. thermic f. SYN: heatstroke. thirst f. an elevation of temperature in infants after reduction of fluid intake, diarrhea, or vomiting; probably caused by reduced available body water, with reduced heat loss by evaporation; an analogous condition in adults is seen when exertion is continued in the face of dehydration. SYN: dehydration f., exsiccation f., inanition f.. three-day f. SYN: phlebotomus f.. Tobia f. SYN: Rocky Mountain spotted f.. traumatic f. elevation of temperature following an injury. SYN: symptomatic f., wound f.. trench f. an uncommon rickettsial f. caused by Bartonella quintana and transmitted by the louse Pediculus humanus, first appearing as an epidemic during the trench warfare of World War I; characterized by the sudden onset of chills and f., myalgia (especially of the back and legs), headache, and general malaise that typically lasts 5 days but may recur. SYN: five-day f., quintan f., shin bone f.. trypanosome f. the febrile stage of sleeping sickness. tsutsugamushi f. SYN: tsutsugamushi disease. typhoid f. an acute infectious disease caused by Salmonella typhi and characterized by a continued f. rising in a steplike curve the first week, severe physical and mental depression, an eruption of rose-colored spots on the chest and abdomen, tympanites, early constipation, diarrhea, and sometimes intestinal hemorrhage or perforation of the bowel; average duration is 4 weeks, although aborted forms and relapses are not uncommon; the lesions are located chiefly in the lymph follicles of the intestines (Peyer patches), the mesenteric glands, and the spleen; antibody titer of the Widal test rises during the infection, and early positive blood and urine cultures become negative, usually results in immunity. SYN: abdominal typhoid, enteric f. (1) , typhoid (2) . undifferentiated type fevers a term applied to illnesses resulting from infection by any virus, that was formerly in the arbovirus group, pathogenic for humans, in which the only constant manifestation is f.; rash, lymphadenopathy, or arthralgia (alone or in combination) may occur in some individuals but not in others; some viruses may induce infections in which undifferentiated type f. is the only manifestation, whereas other viruses may induce in some persons only undifferentiated f., and in other persons similar f. followed by secondary manifestations, e.g., a hemorrhagic f. or encephalitis. undulant f. SYN: brucellosis. [referring to the wavy appearance of the long temperature curve] undulating f. SYN: brucellosis. f. of unknown origin the presence of f. (temperature >101°F or 38.3°C) of unknown cause after intensive investigation. Exact criteria for use of term vary, especially regarding duration of f. and extent of clinical investigation; generally a duration of greater than 1 week (some authors require 2–3 weeks) and thorough inpatient investigation or at least three outpatient visits, including a careful history, physical examination, and laboratory tests such as cultures, serologic studies, and invasive procedures for biopsy and/or culture, as indicated by clinical clues or epidemiological considerations. urethral f. SYN: urinary f.. urinary f. an elevation of temperature, usually slight and transitory, following catheterization of the urethra, or the passage of blood clots, gravel, or a calculus. SYN: catheter f., urethral f.. urticarial f. SYN: schistosomiasis japonica. uveoparotid f. chronic enlargement of the parotid glands and inflammation of the uveal tract accompanied by a long-continued f. of low degree; now recognized as a form of sarcoidosis. SYN: Heerfordt disease. Uzbekistan hemorrhagic f. a viral f. in central Asia probably transmitted by Hyalomma anatolicum. valley f. SYN: primary coccidioidomycosis. Venezuelan hemorrhagic f. a febrile disease caused by the Guanarito virus in Venezuela and characterized by headache, arthralgia, pharyngitis, leukopenia, thrombocytopenia, and hemorrhagic manifestations. viral hemorrhagic f. an epidemic disease, and associated with f., malaise, muscular pain, respiratory tract symptoms, vomiting, and diarrhea; epistaxis, hemoptysis, hematemesis, and subconjunctival hemorrhages occur in severe cases, and body rash and tremors occur in some instances; a disease caused by a number of different viruses in the families Arenoviridae, Bunyviridae, Flaviviridae, Filoviridae, etc. SEE ALSO: hemorrhagic f.. vivax f. SYN: vivax malaria. Wesselsbron f. a mosquito-borne disease of sheep and humans caused by the Wesselsbron disease virus, a member of the family Flaviviridae, and characterized by abortion and lamb mortality in sheep and by f., headache, muscular pains, and mild rash in humans. SYN: Wesselsbron disease. [Wesselsbron, town in South Africa where causative agent first isolated] West African f. SYN: malarial hemoglobinuria. West Nile f. a febrile illness caused by West Nile virus, a member of the family Flaviviridae, and characterized by headache, f., maculopapular rash, myalgia, lymphadenopathy, and leukopenia; spread by Culex mosquitoes from a reservoir in birds. wound f. SYN: traumatic f.. Yangtze Valley f. SYN: schistosomiasis japonica. yellow f. a tropical mosquito-borne viral hepatitis, due to yellow f. virus, a member of the family Flaviviridae, with an urban form transmitted by Aedes aegypti, and a rural, jungle, or sylvatic form from tree-dwelling mammals by various mosquitoes of the Haemagogus species complex; characterized clinically by f., slow pulse, albuminuria, jaundice, congestion of the face, and hemorrhages, especially hematemesis; used to occur in epidemics mainly in port cities, especially in late summer, with 20–40% case fatality rates; immunity to reinfection accompanies recovery. Zika f. an acute disease, probably transmitted by mosquitoes, clinically resembling dengue; caused by Zika virus, a member of the family Flaviviridae. zinc fume f. SYN: brass founder's f..

feverish (fe′ver-ish)
1. SYN: febrile. 2. Having a fever.

Abbreviation for filtration fraction.

Abbreviation for unesterified free fatty acid.

Abbreviation for fresh frozen plasma.

Abbreviation for Fellow of the Faculty of Radiologists (United Kingdom).

Abbreviation for N-formylglycinamide ribotide.

Abbreviation for tetrahydrofolic acid. See 5,6,7,8-tetrahydrofolate dehydrogenase, tetrahydrofolate methyltransferase.

fiber (fi′ber) [TA]
A slender thread or filament. 1. Extracellular filamentous structures such as collagenic or elastic connective tissue fibers. 2. The nerve cell axon with its glial cell or Schwann cell envelope. 3. Elongated, hence threadlike, cells such as muscle cells and the epithelial cells composing the major part of the eye lens. 4. Nutrients in the diet that are not digested by gastrointestinal enzymes. SYN: fibra [TA] , fibre. [L. fibra] A fibers myelinated nerve fibers in somatic nerves, measuring 1–22 μm in diameter, conducting nerve impulses at a rate of 6–120 m/sec. accelerator fibers postganglionic sympathetic nerve fibers originating in the superior, middle, and inferior cervical ganglia of the sympathetic trunk, conveying nervous impulses to the heart that increase the rapidity and force of the cardiac pulsations. SYN: augmentor fibers. adrenergic fibers nerve f.'s that transmit nervous impulses to other nerve cells (or smooth muscle or gland cells) by the medium of the adrenalinelike transmitter substance norepinephrine (noradrenaline). afferent fibers those that convey impulses to a ganglion or to a nerve center in the brain or spinal cord. alpha fibers large somatic motor or proprioceptive nerve fibers with conducting impulses at rates of 80–120 m/sec. anastomosing fibers, anastomotic fibers individual fibers passing from one nerve trunk or muscle bundle to another. anterior external arcuate fibers [TA] See external arcuate fibers. arcuate fibers nervous or tendinous fibers passing in the form of an arch from one part to another. See arcuate fibers of cerebrum, external arcuate fibers, internal arcuate fibers. arcuate fibers of cerebrum [TA] short association fibers that connect adjacent gyri in the cerebral cortex. SYN: fibrae arcuatae cerebri [TA] . argyrophilic fibers reticular connective tissue fibers that react with silver salts and appear black microscopically. association fibers nerve fibers interconnecting subdivisions of the cerebral cortex of the same hemisphere or different segments of the spinal cord on the same side. SYN: endogenous fibers, intrinsic fibers. astral fibers fibers (fibrils) radiating from the centrosphere toward the periphery of the cell as seen with a light microscope; revealed as microtubules under the electron microscope. Cf.:kinetochore fibers, polar fibers. augmentor fibers SYN: accelerator fibers. autonomic nerve fibers [TA] any of the pre- and/or postsynapatic nerve fibers that collectively comprise the sympathetic and parasympathetic parts of the autonomic division of the peripheral nervous system. SYN: neurofibrae autonomicae [TA] , visceral motor fibers. B fibers myelinated fibers autonomic nerves, with a diameter of 2 μm or less, conducting at a rate of 3–15 m/sec. Bergmann fibers filamentous glia fibers traversing the cerebellar cortex perpendicular to the surface. beta fibers nerve fibers that have conduction velocities of 40–70 m/sec. bulbar corticonuclear fibers [TA] nerve fibers projecting from the motor and somatic sensory cortices to motor and sensory relay nuclei of the medulla oblongata, such as the hypoglossal nucleus, accessory nucleus and gracile and cuneate nuclei. See corticonuclear fibers. SYN: fibrae corticonucleares bulbi [TA] . C fibers unmyelinated fibers, 0.4–1.2 μm in diameter, conducting nerve impulses at a velocity of 0.7–2.3 m/sec. cerebellohypothalamic fibers nerve fibers originating from cells of the cerebellar nuclei and projecting, via the superior cerebellar peduncle, to the contralateral hypothalamus, mainly its dorsal, lateral, and posterior areas and dorsomedial nucleus. cerebelloolivary fibers [TA] axons that arise from neurons in the cerebellar nuclei, exit via the superior cerebellar peduncle, cross in its decussation, and descend in association with the central tegmental tract. Depending of their origin, these fibers terminate in the accessory and principal olivary nuclei; anterior and posterior interposed nuclei to the dorsal accessory and medial accessory olivary nuclei respectively, the medial cerebellar nucleus to the medial accessory olivary nucleus, and the lateral cerebellar nucleus to the principal olivary nucleus. SYN: fibrae cerebelloolivares [TA] . cerebellospinal fibers fibers that originate from the fastigial and interposed (primarily the posterior) cerebellar nuclei and descend to the contralateral side of the spinal cord. See fastigiospinal fibers. SEE ALSO: fastigiospinal fibers. cholinergic fibers nerve fibers that transmit impulses to other nerve cells, muscle fibers, or gland cells by the medium of the transmitter substance acetylcholine. chromatic f. SYN: chromonema. circular fibers the circular fibers of the ciliary muscle. SYN: fibrae circulares [TA] , Müller fibers (1) , Müller muscle (2) , Rouget muscle. climbing fibers nerve fibers in the cerebellar cortex that synapse upon smooth branchlets of Purkinje cell dendrites. collagen f., collagenous f. an individual f. that varies in diameter from less than 1 μm to about 12 μm and is composed of fibrils; the fibers' which are usually arranged in bundles, undergo some branching and are of indefinite length; chemically the f. is a glycoprotein, collagen, which yields gelatin upon boiling; they make up the principal element of irregular connective tissue, tendons, aponeuroses, and most ligaments, and occur in the matrix of cartilage and osseous tissue. SYN: white f. (2) . commissural fibers nerve fibers crossing the midline and connecting two corresponding parts or regions of the nervous system. cone f. a part of the cone cell of the retina; the inner cone f. is a slender axon-like part of the cone extending from the cell body to the pedicle located in the outer plexiform layer of the retina; in the outer fovea, where the cones are much elongated, they narrow to an outer cone f., located between the inner segment and the cell body. corticobulbar fibers term formerly used to describe projections of the motor and sensory cortices to nuclei of the rhombencephalon innervating the musculature of the face, tongue, and jaws and some fibers to rhombencephalic relay nuclei; replaced by bullar corticonuclear fibers (to medulla), pontine corticonuclear fibers (to pons), mesencephalic corticonuclear fibers (to midbrain). See these individual entries. corticomesencephalic fibers [TA] axons that originate in the cerebral cortex and terminate in mesencephalic structures such as the tectum, substantia nigra, or tegmentum. SYN: fibrae corticomesencephalicae [TA] . corticonuclear fibers descriptive term connotating fibers from a cortical structure (cerebral or cerebellar) passing to subcortical cell groups; fibers comprising the fibrae corticonucleares bulbi [TA], fibrae corticonucleares pontis [TA] and fibrae corticonucleares mesencephali [TA]; cerebellar corticonuclear fibers (Purkinje cell axons to the cerebellar nuclei). SYN: fibrae corticonucleares [TA] . corticopontine fibers [TA] the fibers that compose the corticopontine tract. SYN: fibrae corticopontinae [TA] . corticoreticular fibers [TA] corticofugal fibers distributed to the reticular formation of the mesencephalon and rhombencephalon. SEE ALSO: corticonuclear fibers. SYN: fibrae corticoreticulares [TA] . corticorubral fibers [TA] nerve fibers projecting from the cerebral cortex (primarily precentral and premotor regions) to the red nucleus of the midbrain. SYN: fibrae corticorubrales [TA] . corticospinal fibers [TA] SYN: pyramidal fibers. corticothalamic fibers a general term designating nerve fibers originating from any area of the cerebral cortex and terminating in the nuclei of the thalamus. cuneocerebellar fibers [TA] SYN: cuneocerebellar tract. cuneospinal fibers [TA] axons that originate in the cuneate nucleus of the medulla oblongata and descend ipsilaterally in the cuneate fasciculus to terminate primarily in the posterior horn of the spinal cord in cervical and upper thoracic levels. SYN: fibrae cuneospinales [TA] . delta fibers nerve fibers with conduction velocities in the range of 8–30 m/sec. dentatorubral fibers nerve fibers arising in the dentate nucleus of the cerebellum and projecting, via the superior cerebellar peduncle and its decussation, to the contralateral red nucleus of the midbrain. SYN: fibrae dentatorubrales. dentatothalamic fibers nerve fibers projecting from the dentate nucleus of the cerebellum to the contralateral thalamus via the superior cerebellar peduncle (and its decussation); enter the thalamus as one component of the thalamic fasciculus. dentinal fibers, dental fibers 1. the processes of the pulpal cells, the odontoblasts, which extend in radial fashion through the dentin to the dentoenamel junction and are contained within the dentinal tubules; SYN: Tomes fibers. 2. the intertubular fine collagenous fibers that with the dentinal ground substance infiltrated with calcium salts constitutes the dentinal matrix. depressor fibers sensory nerve fibers having pressure-sensitive nerve endings in the wall of certain arteries capable of activating blood pressure-lowering brainstem mechanisms when stimulated by an increase in intraarterial pressure. dietary f. the plant polysaccharides and lignin that are resistant to hydrolysis by the digestive enzymes in humans. efferent fibers those fibers conveying impulses to effector tissues (muscle: smooth, cardiac or striated; or glands) in the periphery; those fibers exiting a specific cell group ( i.e., efferent fibers of the basilar pons), used in reference to a cell group. elastic fibers fibers that are 0.2–2 μm in diameter but may be larger in some ligaments; they branch and anastomose to form networks and fuse to form fenestrated membranes; the fibers and membranes consist of microfibrils about 10 nm wide and an amorphous substance containing elastin. SYN: yellow fibers. enamel fibers SYN: prismata adamantina, under prisma. endogenous fibers SYN: association fibers. exogenous fibers nerve fibers by which a given region of the central nervous system is connected with other regions; the term applies to both afferent and efferent f. connections. external arcuate fibers they include: 1) posterior external arcuate fibers [TA] that arise from cells in the accessory or lateral cuneate nucleus and pass to the cerebellum; 2) anterior external arcuate fibers [TA] that arise from the arcuate nuclei at the base of the medulla oblongata and pass around the lateral surface of the medulla; both enter the cerebellum as components of the restiform portion of the inferior cerebellar peduncle. SYN: fibrae arcuatae externae. fastigiobulbar fibers nerve fibers projecting from the fastigial nuclei of the cerebellum to the brainstem; crossed and uncrossed fibers that terminate mainly in the vestibular and reticular nuclei, and in the medial accessory olivary nucleus. fastigiospinal fibers crossed descending fibers originating in the fastigial nucleus of the cerebellum and ending in the spinal cord gray matter at cervical, and possibly lower, levels. frontopontine fibers [TA] a large group of fibers arising from the frontal lobe of the cerebral hemisphere, especially the precentral gyrus, descending in the internal capsule, farther caudally composing the medial part of the crus cerebri through which they extend caudalward to end in the gray matter (pontine nuclei) of the ventral part of the pons. SEE ALSO: corticopontine tract. SYN: fibrae frontopontinae [TA] . gamma fibers nerve fibers that have a conduction rate of 15–40 m/sec. SEE ALSO: gamma efferent. Gerdy fibers SYN: superficial transverse metacarpal ligament. gracilespinal fibers [TA] axons that arise from neurons of the gracile nucleus of the medulla oblongata and descend ipsilaterally in the gracile fasciculus to terminate primarily in the posterior horn of the spinal cord in lower thoracic and lumbosacral levels. SYN: fibrae gracilispinales [TA] . Gratiolet fibers SYN: optic radiation. gray fibers SYN: unmyelinated fibers. hypothalamocerebellar fibers nerve fibers originating from cells in the hypothalamus and projecting to the cerebellar cortex and nuclei. hypothalamospinal fibers [TA] a group of fibers that originates primarily from the paraventricular nucleus and lateral and posterior hypothalamic areas, descends ipsilaterally through the ventrolateral brainstem and into the lateral funiculus of the spinal cord, and terminates in relation to neurons of the intermediolateral nucleus. SYN: fibrae hypothalamospinales [TA] . inhibitory fibers nerve fibers that inhibit the activity of the nerve cells with which they have synaptic connections, or of the effector tissue (smooth muscle, heart muscle, glands) in which they terminate. intercolumnar fibers SYN: intercrural fibers of superficial ring. intercrural fibers of superficial ring [TA] horizontal arched fibers that pass from the inguinal ligament across the medial and lateral crura of the superficial inguinal ring. SYN: fibrae intercrurales anuli inguinalis superficialis [TA] , intercolumnar fasciae, intercolumnar fibers. internal arcuate fibers [TA] fibers that arise in the cuneate and gracile nuclei, pass in a curving course across the midline of the medulla oblongata, and form the contralateral medial lemniscus; may also designate other fibers such as those of the olivocerebellar tract that arch through the substance of the medulla and may traverse the sensory decussation. SYN: fibrae arcuatae internae [TA] . intrafusal fibers muscle fibers present within a neuromuscular spindle. intrathalamic fibers [TA] fibers that arise in one nucleus of the dorsal thalamus and terminate in another. SYN: fibrae intrathalamicae [TA] . intrinsic fibers SYN: association fibers. James fibers atrio-His bundle connections thought to be the basis for the short P-R interval syndrome; these fibers should be distinguished from the controversial internodal tracts of the atrium, sometimes referred to as “James tracts.” SYN: James tracts. kinetochore fibers fibers of the mitotic spindle attached to the centromere and extending toward the poles. Cf.:astral fibers, polar fibers. Korff fibers argyrophilic fibers that pass between odontoblasts at the periphery of the dental pulp and fan out into the dentin. Kühne f. artificial muscle f. made by filling the intestine of an insect with a growth of myxomycetes; used to demonstrate the contractility of protoplasm. fibers of lens the elongated cells of ectodermal origin forming the substance of the crystalline lens of the eye. SYN: fibrae lentis. long association fibers [TA] nerve fibers interconnecting lobes or gyri of the cerebral cortex of the same hemisphere that are not immediately adjacent to each other; nerve fibers connecting noncontiguous segments of the spinal cord on the same side; fibers that interconnect distant points. SYN: fibrae associationes longae [TA] . longitudinal pontine fibers [TA] See longitudinal pontine fasciculi, under fasciculus. SYN: fibrae pontis longitudinales [TA] . Mahaim fibers paraspecific fibers originating from the A-V node, the His bundle, or the bundle branches and inserting into the ventricular myocardium; they are potential pathways for reentrant dysrhythmias. SYN: nodoventricular fibers. medullated nerve f. SYN: myelinated nerve f.. meridional fibers of ciliary muscle [TA] the longitudinal fibers of the ciliary muscle. SYN: fibrae meridionales muscularis ciliaris [TA] . mesencephalic corticonuclear fibers [TA] nerve fibers projecting primarily from the motor cortex to motor nuclei of the mesencephalon such as the oculomotor and trochlear; these inputs are relayed via nuclei located adjacent to these motor nuclei. See corticonuclear fibers. SYN: fibrae corticonucleares mesencephali [TA] . mossy fibers highly branched nerve f.'s in the cerebellar cortex that terminate in rosette formations and synapse upon granule cell dendrites. motor fibers nerve fibers that transmit impulses that activate effector cells, e.g., in muscle or gland tissue. Müller fibers 1. SYN: circular fibers. 2. sustentacular neuroglial cells of the retina, running through the thickness of the retina from the internal limiting membrane to the bases of the rods and cones where they form a row of junctional complexes. SYN: Müller radial cells, sustentacular fibers of retina. myelinated nerve f. an axon enveloped by a myelin sheath formed by oligodendroglia cells (in brain and spinal cord) or Schwann cells (in peripheral nerves). SYN: medullated nerve f.. Nélaton fibers SYN: Nélaton sphincter. nerve f. the axon of a nerve cell, ensheathed by oligodendroglia cells in brain and spinal cord, and by Schwann cells in peripheral nerves. nodoventricular fibers SYN: Mahaim fibers. nonmedullated fibers SYN: unmyelinated fibers. nuclear bag f. the largest type of intrafusal muscle fibers in a neuromuscular spindle, containing a central aggregation of nuclei (nuclear bag). nuclear chain f. the shortest and most numerous type of intrafusal muscle fibers in a neuromuscular spindle, containing a single row of centrally positioned nuclei. nucleocortical fibers general term for projections from a nucleus to an overlying cortical structure; specifically used to designate axons of cerebellar nuclear cells that project to the cerebellar cortex (cerebellar nucleocortical fibers) where they end as mossy fibers. oblique fibers of muscular layer of stomach [TA] the smooth muscle fibers of the innermost layer of the muscular coat of the stomach; the fibers occur chiefly at the cardiac end of the stomach and spread over the anterior and posterior surfaces. SYN: fibrae obliquae tunicae muscularis [TA] . occipitopontine fibers [TA] a group of fibers originating in the occipital lobe of the cerebral hemisphere and descending in the internal capsule and lateral part of the crus cerebri to the pontine nuclei of the basilar part of the pons. SEE ALSO: corticopontine tract. SYN: fibrae occipitopontinae [TA] . occipitotectal fibers [TA] fibers originating in visual regions of the occipital lobe and passing, via the retrolenticular limb of the internal capsule, to the tectum where they end mainly in the superior colliculus. SYN: fibrae occipitotectales [TA] . olivocochlear fibers See olivocochlear tract. olivospinal fibers a slender bundle of nerve fibers in the peripheral zone of the lateral funiculus of the spinal cord, composed, more likely, of spinoolivary fibers than of olivospinal fibers. SYN: fibrae olivospinales [TA] , Helwig bundle. osteocollagenous fibers fine collagenous fibers in the matrix of osseous tissue. osteogenetic fibers the fibers in the osteogenetic layer of the periosteum. parietopontine fibers [TA] a system of fibers originating in the parietal lobe of the cerebral hemisphere that descend in the internal capsule and lateral part of the crus cerebri to terminate in the pontine nuclei in the ventral part of the pons. SEE ALSO: corticopontine tract. SYN: fibrae parietopontinae [TA] . pectinate fibers SYN: pectinate muscles, under muscle. perforating fibers bundles of collagenous fibers that pass into the outer circumferential lamellae of bone or the cementum of teeth. SYN: Sharpey fibers. periodontal f. desmodentium. periodontal ligament fibers SYN: desmodentium. periventricular fibers [TA] a heterogeneous system of thin nerve fibers in the periventricular gray matter of the hypothalamus; the dorsal longitudinal fasciculus is a caudal continuation of the system. SYN: fibrae periventriculares [TA] . pilomotor fibers nerve fibers that innervate the erector muscles of hair follicles responsible for piloerection. polar fibers those fibers of the mitotic spindle extending from the two poles of the spindle toward the equator. Cf.:astral fibers, kinetochore fibers. pontine corticonuclear fibers [TA] nerve fibers projecting from the motor and sensory cortices to motor and sensory relay nuclei in the pontine tegmentum such as the facial, abducens, and trigeminal nuclei; fibers may be direct or relayed via the adjacent reticular nuclei. See corticonuclear fibers. SYN: fibrae corticonucleares pontis [TA] . pontocerebellar fibers [TA] fibers arising from the nuclei of the basilar pons and primarily crossing the midline (there is a modes uncrossed projection), centering the cerebellum via the middle cerebellar peduncle and terminating as mossy fibers in the cerebellar cortex. SYN: fibrae pontocerebellares [TA] . postcommissural fibers [TA] fibers in the column of fornix that pass caudal (posterior) to the anterior commissure to enter the mammillary nuclei; the largest part of the column of fornix. SYN: fibrae postcommissurales [TA] . posterior external arcuate fibers [TA] See external arcuate fibers. postganglionic fibers a f. whose cell body is located in an autonomic (motor) ganglion and whose peripheral process will terminate on smooth muscle, cardiac muscle, or glandular epithelium; associated with sympathetic or parasympathetic parts of the autonomic nervous system. postganglionic nerve f. [TA] See postganglionic. precollagenous fibers immature, argyrophilic fibers. precommissural fibers [TA] fibers in the column of fornix that pass rostral (anterior) to the anterior commissure to enter primarily the septal nuclei. SYN: fibrae precommissurales [TA] . preganglionic fibers a f. whose cell body is located in an autonomic nucleus in the spinal cord or brain stem and whose axon terminates in an autonomic (motor) ganglion; found in nerves conveying sympathetic or parasympathetic fibers. preganglionic nerve fibers See preganglionic. SYN: neurofibrae preganglionicae. pressor fibers sensory nerve fibers whose stimulation causes vasoconstriction and rise of blood pressure. pretectoolivary fibers [TA] fibers originating from the pretectal nuclei and projecting primarily to the ipsilateral medial accessory olivary nucleus. SYN: fibrae pretectoolivares [TA] . projection fibers nerve fibers connecting the cerebral cortex with other centers in the brain or spinal cord; fibers arising from cells in the central nervous system that pass to distant loci. Prussak fibers elastic and connective tissue fibers bounding the pars flaccida membranae tympani. Purkinje fibers SYN: subendocardial branches of atrioventricular bundles, under branch. pyramidal fibers the fibers that compose the corticospinal tract. SEE ALSO: corticospinal tract. SYN: corticospinal fibers [TA] , fibrae corticospinales [TA] , fibrae pyramidales. raphespinal fibers nerve fibers originating from cells of the nuclei raphe magnus, pallidus, and obscurus of the pons and medulla and terminating in the spinal cord gray matter; fibers involved in the descending inhibition of nociceptive input in the dorsal (posterior) horn; they contain serotonin. red fibers red striated muscle fibers that are rich in sarcoplasm, myoglobin, and mitochondria; they are smaller in diameter and contract more slowly than white fibers. Reissner f. a rodlike, highly refractive f. running caudally from the subcommissural organ throughout the length of the central canal of the brainstem and spinal cord. Remak fibers SYN: unmyelinated fibers. reticular fibers the collagen (type III) fibers forming the distinctive loose connective tissue stroma of embryonic tissues, mesenchyme, red pulp of the spleen, cortex and medulla of lymph nodes, and the hematopoietic compartments of bone marrow and accounting for a substantial portion of the collagen fibers of the skin, blood vessels, synovial membrane, uterine tissue, and granulation tissue; characterized by organization as a reticular meshwork of fine filaments and by an affinity for silver and for periodic acid-Schiff stains. Retzius fibers stiff fibers in Deiters cells. rod f. a part of the rod cell of the retina that extends to either side of the cell body; the inner rod f. terminates in the spherule, a synaptic ending located in the outer plexiform layer. Rosenthal f. an oval or elongated eosinophilic mass believed to represent a modified process of an astrocyte; seen in large numbers in certain slowly growing astrocytomas and areas of chronic reactive gliosis. rubroolivary fibers [TA] axons that arise from cells of the parvocellular part of the red nucleus, descend ipsilaterally as one component of the central tegmental tract, and terminate primarily in the principal olivary nucleus. SYN: fibrae rubroolivares [TA] . Sappey fibers nonstriated muscular fibers in the check ligaments of the eyeball. Sharpey fibers SYN: perforating fibers. short association fibers [TA] nerve fibers that may interconnect adjacent lobes or gyri of the cerebral cortex of the same hemisphere or contiguous segments of the spinal cord on the same side; fibers that interconnect close or adjacent points. SYN: fibrae associationes breves [TA] . skeletal muscle fibers multinucleated contractile cells varying from less than 10 to 100 μm in diameter and from less than 1 mm to several centimeters in length; the f. consists of sarcoplasm and cross-striated myofibrils, which in turn consist of myofilaments; human skeletal muscles are a mixture of red, white, and intermediate type fibers. somatic nerve fibers [TA] afferent or efferent fibers distributed outside the body cavities, i.e., to the parietes; the majority of somatic afferent fibers conduct impulses centrally stimulating conscious sensation; all somatic efferent fibers stimulate somatic (voluntary/striated/skeletal) muscle. SYN: neurofibrae somaticae [TA] . spindle f. mitotic spindle. spinocuneate fibers axons that originate from cells in the posterior horn of cervical and upper thoracic spinal levels, ascend ipsilaterally in the cuneate fasciculus, and terminate in the cuneate nucleus. These are part of the postsynaptic–dorsal column system. SYN: fibrae spinocuneatae [TA] . spinogracile fibers [TA] axons that originate from neurons in the posterior horn of lower thoracic and lumbosacral spinal cord levels, ascend ipsilaterally in the gracile fasciculus, and terminate in the gracile nucleus. These are part of the postsynaptic–dorsal column system. SYN: fibrae spinograciles [TA] . spinohypothalamic fibers [TA] axons that originate in the spinal cord gray matter, ascend as part of the anterolateral system, and terminate in the hypothalamus SYN: fibrae spinohypothalamicae [TA] . spinomesencephalic fibers [TA] a composite group of fibers traveling in the spinal lemniscus (anterolateral system) and ending in the mesencephalon; includes spinotectal fibers [TA] to the deeper layers of the superior colliculus and spinoperiaqeductal fibers [TA] that terminate in the periaqueductal gray matter. SYN: fibrae spinomesencephalicae [TA] . spinoolivary fibers [TA] fibers that arise in the spinal cord and ascend primarily on the ipsilateral side to terminate in the accessory nuclei of the inferior olivary complex. SYN: fibrae spinoolivares [TA] . spinoperiaqueductal fibers [TA] axons originating from cell bodies of the posterior horn, ascending as part of the contralateral anterolateral system, and terminating in the periaqueductal gray of the mesencephalon; involved in descending pathways for pain suppression. SEE ALSO: spinomesencephalic fibers. SYN: fibrae spinoperiaqueductales [TA] . spinoreticular fibers [TA] nerve fibers originating from the spinal cord and terminating in the reticular formation of the brainstem; some ascend as part of the anterolateral system. SYN: fibrae spinoreticulares [TA] , spinoreticular tract [TA] . spinotectal fibers [TA] axons originating from cell bodies in the posterior horn, crossing in the anterior white commissure, ascending as part of the anterolateral system, and primarily terminating in the deeper layers of the superior colliculus. SEE ALSO: spinomesencephalic fibers. SYN: fibrae spinotectales [TA] . stress fibers long bundles of microfilaments made up of actin; believed to be involved in the attachment of cultured cells to a substratum and also in the determination of the shape of cells such as fibroblasts; may be involved in cellular mobility. striatonigral fibers SYN: strionigral fibers. strionigral fibers nerve fibers originating from cells of the caudate and putamen and terminating mainly in the pars reticulata of the substantia nigra; they utilize GABA and substance P. SYN: striatonigral fibers. sudomotor fibers postganglionic and cholinergic sympathetic nerve fibers that innervate the sweat glands. sustentacular fibers of retina SYN: Müller fibers (2) . T f. a f. that branches at right angles to the right and left; term used to describe the branching patterns of granular cell axons in the molecular layer of the cerebellum. tautomeric f.s nerve fibers of the spinal cord that do not extend beyond the limits of the spinal cord segment in which they originate. tectoolivary fibers [TA] fibers that originate in the deep layers of the superior colliculus and project primarily to the contralateral medial accessory olivary nucleus. SYN: fibrae tectoolivares [TA] . tectopontine fibers [TA] fibers arising in the tectum of the mesencephalon and terminating in the ipsilateral nuclei of the basilar pons and in the reticulotegmental nucleus. SYN: fibrae tectopontinae [TA] . tectoreticular fibers [TA] fibers that originate in the superior colliculus and project bilaterally to the reticular formation, primarily that of the midbrain. SYN: fibrae tectoreticulares [TA] . temporopontine fibers [TA] a f. group originating in the cerebral cortex of the temporal lobe, particularly the superior and middle temporal gyri, following the sublenticular limb of the internal capsule into the lateral margin of the crus cerebri in which it descends to its termination in the pontine nuclei in the basilar part of the pons. SEE ALSO: corticospinal tract. SYN: fibrae temporopontinae [TA] . thalamocortical fibers a general term identifying nerve fibers arising from nuclei of the thalamus and projecting to, and terminating in, the cerebral cortex. Tomes fibers SYN: dentinal fibers (1) . transseptal fibers nonelastic fibers running from tooth to tooth over the crest of the alveolus. transverse pontine fibers [TA] fibers arising from the pontine nuclei, decussate and pass into the cerebellum as the middle cerebellar peduncles. SYN: fibrae pontis transversae [TA] . unmyelinated fibers a f. having no myelin covering (CNS); a naked axon; in the PNS represented by all axons lying in troughs in a single Schwann cell (Schwann cell unit); a slow conducting f.. SYN: gray fibers, nonmedullated fibers, Remak fibers. vasomotor fibers postganglionic visceral efferent fibers innervating the smooth muscles of vessel walls. visceral motor fibers SYN: autonomic nerve fibers. Weitbrecht fibers SYN: retinaculum of articular capsule of hip. white f. 1. white mammalian muscle fibers; larger in diameter than red fibers they have less myoglobin, sarcoplasm, and mitochondria, and contract more quickly; 2. SYN: collagen f.. yellow fibers SYN: elastic fibers. zonular fibers [TA] delicate fibers that pass from the equator of the lens to the ciliary body, collectively known as the ciliary zonule. SYN: fibrae zonulares [TA] .

fiberoptic (fi-ber-op′tik)
Pertaining to fiberoptics.


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