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At least 19 recordsLinked to original sources
PubMed1992

Comparative vaginal cytology of the estrous cycle of black-footed ferrets (Mustela nigripes), Siberian polecats (M. eversmanni), and domestic ferrets (M. putorius furo).

Vaginal cytology and vulva size were used to characterize the reproductive cycle of female black-footed ferrets (Mustela nigripes), Siberian polecats (M. eversmanni), and domestic ferrets (M. putorius furo). Emphasis was on black-footed ferrets because of the need to breed these critically endangered animals and on Siberian polecats because of the close taxonomic relationship to black-footed ferrets. Vaginal cytology of the 3 species of ferret is similar. Proestrus was characterized by an increasing percentage of superficial epithelial cells and enlargement of the vulva. During estrus, superficial cells were usually greater than or equal to 90% of epithelial cells in the vaginal lavage and after several days were fully keratinized. Neutrophils were more common during all stages of the estrous cycle in domestic ferrets than they were in the other species. Following copulation, percentage of superficial calls in the vagina declined and vulva swelling subsided. Large cells, probably of uterine symplasma origin, were observed in vaginal lavages following whelping or pseudopregnancy. Vaginal cytology is extremely useful in the reproductive management of black-footed ferrets and Siberian polecats. Knowledge of normal vaginal cytology could be applied to the diagnosis of female reproductive abnormalities in all 3 species.

Animals↗
PubMed1991

Distribution of choline acetyltransferase immunoreactive axons and terminals in the rat and ferret brainstem.

A survey was made of the density of the cholinergic innervation of different parts of the brainstem of the rat and ferret. Sections of rat and ferret brainstems were stained for choline acetyltransferase (ChAT) immunoreactivity by using a sensitive immunocytochemical method. Adjacent sections were stained for acetylcholinesterase activity or Nissl substance. The density of the distribution of fine calibre, varicose ChAT-positive axons, assumed to represent cholinergic terminals, was categorised arbitrarily into high, medium, or low. A high density of ChAT-positive terminals was found in all or parts of these structures: interpeduncular nucleus, superficial grey layer of the superior colliculus (ferret), intermediate layers of the superior colliculus, lateral part of the central grey (rat), an area medial to the parabigeminal nucleus (rat), pontine nuclei, ventral tegmental nucleus (rat), midline pontine reticular formation, and an area ventral to the exit point of the 5th nerve (ferret). A medium density of ChAT-positive terminals was observed in all or parts of: the substantia nigra zona compacta (ferret), ventral tegmental area (ferret), superficial grey layer of the superior colliculus, intermediate and deep layers of the superior colliculus, lateral central grey, area medial to the parabigeminal nucleus, inferior colliculus, dorsal tegmental nucleus, ventral tegmental nucleus (ferret), pontine nuclei, ventral nucleus of the lateral lemniscus (ferret), midline pontine reticular formation, ventral cochlear nucleus, dorsal cochlear nucleus, lateral superior olive, spinal trigeminal nuclei, prepositus hypoglossal nucleus, lateral reticular nucleus, paragigantocellular nucleus, and the dorsal column nuclei including the cuneate, external cuneate, and gracile nuclei. A low density of ChAT-positive terminals was seen throughout the remainder of the brainstem of the rat and ferret, but these terminals were absent from the medial superior olive, substantia nigra zona reticulata (rat), and the central part of the ferret lateral superior olive. A pericellular-like distribution of ChAT-positive terminals was observed in the ventral cochlear nucleus and in association with some of the cells of the nucleus of the mesencephalic tract of the trigeminal nerve. A climbing fibre type arrangement of ChAT-positive terminals was found in the substantia nigra zona compacta (ferret) and medial reticular formation. In general, the distribution of staining for AChE activity reflected that of the distribution of ChAT immunoreactivity in the brainstem, except in a few regions where there were also species differences in the distribution of ChAT-positive terminals, e.g., in the superficial grey layer of the superior colliculus and in the substantia nigra.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1990

Photoperiodic regulation of gonadal growth and pulsatile luteinizing hormone secretion in male ferrets.

Testicular growth was monitored in male ferrets subjected to one of the following photoperiodic treatments begun at weaning (8 weeks of age): 8 hr light/day (short days), 18 hr light/day (long days), or short days followed by transition to long days at either 10, 12, or 14 weeks of age. Mean ages to achieve adult testis width of greater than or equal to 12 mm were 27.5 +/- 1.3, 25.0 +/- 1.5, 23.6 +/- 2.9, 20.0 +/- 0.8, and 21.2 +/- 1.0 weeks in ferrets raised from weaning in long days, raised from weaning in short days, and transferred from short to long days at 10, 12, or 14 weeks, respectively. This criterion was met significantly earlier by ferrets experiencing the photoperiod transition at 12 or 14 weeks of age than by ferrets housed in long days from weaning. At the end of the experiment (30 weeks of age), mean testis width was significantly smaller in ferrets raised in long days from weaning or transferred to long days at 10 weeks of age, compared to that of the other three groups (p less than 0.05). In a second experiment, photoperiod experience with long or short days was begun at birth, and testicular size was monitored for a longer period of time. The time courses for testicular maturation were similar to that obtained when these treatments began at weaning. By 40 weeks of age, mean testis width of ferrets raised in long days was comparable to that of ferrets raised in short days. A third study determined that the retarded testicular growth observed in ferrets exposed to long days from weaning was correlated with diminished pulsatile luteinizing hormone (LH) secretion. At 28 weeks of age, mean LH pulse frequency was 0.86 +/- 0.09 pulses/hr in ferrets undergoing spontaneous puberty in short days or photoinduced puberty after a short-to-long-day transition; pulse frequency was significantly lower (0.46 +/- 0.26 pulses/hr; p less than 0.05) in ferrets raised in long days. These results indicate that gonadal growth can be precociously induced in male ferrets by exposure to a sequence of short days followed by long days, and that the absence of sufficient prepubertal exposure to short days compromises pulsatile LH secretion and rate of gonadal growth. Experience with short days during development may be necessary for manifestation of stimulatory responses to long days.

Aging↗
PubMed1990

Effects of yohimbine on bradycardia and duration of recumbency in ketamine/xylazine anesthetized ferrets.

Eleven adult ferrets (Mustela putorius furo) were anesthetized with ketamine hydrochloride (25 mg/kg, IM) and xylazine hydrochloride (2 mg/kg, IM). Fifteen minutes post-ketamine/xylazine injection, ferrets were treated with yohimbine hydrochloride at a dose of 0.5 mg/kg, or an equal volume of physiologic saline, intramuscularly. Each ferret served as its own control by randomly receiving both treatments with a minimum interval of 2 weeks between treatments on any one ferret. At 15 minutes post-ketamine/xylazine injection, mean heart rate measurements for both treatment groups were 27% less than the mean heart rate measurement reported for unanesthetized ferrets. Intramuscular administration of yohimbine antagonized the ketamine/xylazine induced bradycardia in 10 of the 11 ferrets, (p = 0.0001). In yohimbine treated ferrets, an increase in mean heart rate measurement was noted 5 minutes after the intramuscular administration of yohimbine, and followed, over the next 15 minutes, by a progressive increase in mean heart rate. However, a corresponding decrease in mean heart rate measurement was observed in saline treated controls. Fifteen minutes after the injection of yohimbine, the mean heart rate measurement of yohimbine treated animals had increased to 194 beats per minute. This mean heart rate measurement is nearly 30% greater than the mean heart rate of 150 beats per minute measured at 15 minutes post-saline injection in saline treated controls. Also, yohimbine treatment significantly reduced duration of recumbency in 10 of 11 ferrets (p = 0.0001). Mean duration of recumbency for yohimbine treated ferrets was 41 +/- 9.7 minutes, whereas mean duration of recumbency for saline treated ferrets was determined to be 80 +/- 11.4 minutes.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1992

Bile salt stimulated lipase: comparative studies in ferret milk and lactating mammary gland.

Bile salt stimulated lipase (BSSL) activity is 10-20 times higher in ferret milk than in human milk. We have used the ferret to study BSSL activity in lactating mammary gland and in mammary cells isolated by hyaluronidase-collagenase treatment followed by Ficoll gradient centrifugation. Furthermore, we have compared the characteristics of BSSL in the tissue preparations (homogenate or cells) to BSSL of ferret milk and to BSSL purified from ferret and human milk. The characteristics of BSSL in ferret mammary gland preparations and milk were similar to those of human milk BSSL--absolute requirement of primary bile salts, pH optimum of 7.5-9.0, stability at pH 3-9 and inhibition by eserine (physostigmine) and by serum. Purified ferret milk BSSL had a lower molecular weight (90kD) than did human milk BSSL (125 kD). There was an 86% homology of the N-terminal amino acid sequence between BSSL of ferret and of human milk. The marked similarity in characteristics between BSSL in ferret and human milk and the high activity of BSSL in ferret milk (520 U/mL colostrum and 250 U/mL mature milk) indicate that this species is an ideal animal model for the study of the synthesis and secretion of this digestive lipase which constitutes a significant portion (1-2%) of total milk protein.

Amino Acid Sequence↗
PubMed1991

Quantitative light and scanning electron microscopy of ferret sperm.

Sperm were obtained via electroejaculation from Domestic ferret, (Mustela putorius furo), Siberian ferret (M. eversmanni), Black-footed ferret (M. nigripes), and a hybrid between Siberian and Domestic, called the Fitch ferret (M. sp.). Comparisons of sperm were made by four different microscopy techniques to determine whether differences exist among species. First, Nomarski differential interference microscopy could be used to distinguish domestic ferret sperm from the others on the basis of the structure of the posterior part of the acrosome. Second, both silver staining, which demonstrates argentophilic protein distribution, and scanning electron microscopy (SEM), revealed differences among the morphology of sperm for each species; variation in the unique appearance of the acrosome in ferret sperm was detected especially well by SEM. To quantify differences in morphology, five sperm head parameters were measured using image analysis; light microscopy produced significantly larger values than did SEM (all parameters and all species but Fitch), and there were significant differences owing to species for all parameters but one. Generally, our data demonstrate the value of complementary techniques to distinguish among sperm of closely related species and more specifically may help establish evolutionary relationships among the ferret species studied. In addition, they provide baseline data important for the captive breeding of the endangered Black-footed ferret.

Acrosome↗
PubMed1992

Malignant lymphoma in ferrets: clinical and pathological findings in 19 cases.

The clinical and pathological findings in 19 ferrets (Mustela putorius furo) with malignant lymphoma are reviewed. Peripubescent ferrets had rapidly progressive stage IV high grade immunoblastic or small non-cleaved cell lymphoma. Adult ferrets had stage II or IV low grade diffuse small lymphocytic (DSL) lymphoma, stage IV high grade small non-cleaved cell lymphoma, or stage IV high grade immunoblastic polymorphous (IBP) lymphoma. Three ferrets had concurrent IBP and DSL lymphoma involving different organs. The IBP admixture of immunoblasts, large atypical lymphocytes, Reed-Sternberg-like cells, lymphoblasts and small lymphocytes has been associated with certain retrovirally associated lymphomas and nodal hyperplasias in man, non-human primates and cats. Aleutian disease, a parvovirus-induced lymphoproliferative disease, also involves clinical and histological features similar to certain lymphomas in ferrets. Seven ferrets tested were seronegative for feline leukaemia virus antigen. Only one of eight ferrets was positive for Aleutian parvovirus antibody. The clinical and pathological findings are suggestive of a viral aetiology for certain lymphomas in ferrets.

Animals↗
PubMed1991

Pulmonary vascular pressure profile in adult ferrets: measurements in vivo and in isolated lungs.

We have determined the vascular pressure profile in lungs of adult ferrets utilizing an anaesthetized open chested preparation and have compared the pressure profile in vivo with that in isolated, perfused lungs. Ten adult ferrets, mean body weight 980 +/- 108 g, were studied. For in vivo measurements, five ferrets were anaesthetized, mechanically ventilated and the left chest wall resected. Pressures were measured in the pulmonary artery, left atrium and by micropuncture, in 20-50 microns diameter subpleural arterioles and venules. During micropuncture, ventilation was stopped for 1-2 min and the lungs kept distended at an airway pressure of 6 cmH2O. Left atrial pressure was raised to approximately 8 cmH2O with saline infusion so that lungs were in Zone 3. Cardiac output was measured by thermodilution. Lungs of five other ferrets were isolated and perfused with a steady flow roller pump. In these lungs blood flow was adjusted so that pulmonary artery pressure was similar to that in anaesthetized ferrets, with airway and left atrial pressures at 6 and 8 cmH2O respectively (Zone 3). Blood haematocrit (35 +/- 7%) was similar in the two groups. In lungs of anaesthetized ferrets total arteriovenous pressure drop was 12.1 +/- 1.9 cmH2O, with cardiac output being 210 +/- 80 ml kg body weight-1 min-1. Fractional resistance in arteries was 37%, 37% in microvessels and 26% in veins. In isolated ferret lungs, though blood flow was only 48 +/- 10 ml kg body wt-1 min-1 for the same total arteriovenous pressure drop as in vivo, the longitudinal distribution of vascular resistance was similar to that in live ferrets.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1991

Helicobacter mustelae-induced gastritis and elevated gastric pH in the ferret (Mustela putorius furo).

Helicobacter mustelae has been cultured from the stomachs of ferrets with chronic gastritis; the lesions in the stomach have many of the same histological features seen in H. pylori gastritis in humans. To determine whether H. mustelae-negative ferrets with normal gastric mucosa were susceptible to colonization and whether gastritis developed after infection, four H. mustelae-negative ferrets treated with cimetidine were inoculated orally on two successive days with 3 ml (1.5 x 10(8) CFU) of H. mustelae; eight age-matched H. mustelae-negative ferrets served as controls. All four ferrets became colonized; H. mustelae persisted through week 24 of the study, as determined by positive gastric culture, tissue urease, and Warthin-Starry staining of gastric tissue. Superficial gastritis developed in the oxyntic gastric mucosa, and a full-thickness gastritis, composed primarily of lymphocytes and plasma cells plus small numbers of neutrophils and eosinophils, was present in the antrum. The inflammation was accompanied by an elevation of immunoglobulin G antibody to H. mustelae. At 4 weeks post-inoculation, the four infected (experimental) ferrets developed an elevated gastric pH (4.0 to 5.2) for 2 weeks. The eight control ferrets did not have gastritis; H. mustelae could not be demonstrated in gastric tissue via culture, nor was there an immune response to the bacteria. In ferrets, H. mustelae readily colonizes the stomach and produces a gastritis, a significant immune response, and, like H. pylori infection in humans, a transient elevated gastric pH after Helicobacter infection.

Animals↗
PubMed1992

Expression of Na(+)-K(+)-ATPase alpha 1- and alpha 3-isoforms in adult and neonatal ferret hearts.

We have demonstrated previously that in adult ferret heart two alpha-subunit isoforms of the Na(+)-K(+)-ATPase, alpha(+) and alpha, are expressed. The alpha(+)-isoform may comprise either alpha 2-, or alpha 3-, or both isoforms. The present studies further characterize the alpha(+)-isoform. The alpha(+)-isoform of ferret heart did not react with an alpha 2-specific monoclonal antibody, but rather with two different alpha 3-specific polyclonal antibodies. Electrophoretic mobility of the alpha(+)-isoform in sodium dodecyl sulfate polyacrylamide gel electrophoresis is slower than that of the alpha 2-isoform, but similar to that of the alpha 3-isoform. Limited proteolytic peptide mapping was performed using Staphylococcus aureus V8. Proteolytic fragments were then immunostained with an alpha 3-specific antibody. The peptide maps of ferret heart alpha(+)-isoform and rat brain alpha 3-isoform were identical, as were those of ferret heart alpha(+)-isoform and ferret brain alpha 3-isoform. These results indicate that the alpha(+)-isoform of ferret heart is an alpha 3-isoform. During postnatal development, the same isoforms expressed in the adult ferret heart (alpha 1 and alpha 3), were also expressed in neonatal heart. In adult or neonatal heart alpha 2-isoform was not detectable. Relative abundances of the isoforms in ventricular and atrial tissues differed. Compared with ventricular tissue, left and right atrial tissues expressed much less alpha 3 than alpha 1. It is concluded that, unlike rat heart, alpha 1- and alpha 3-isoforms are expressed in adult ferret heart.(ABSTRACT TRUNCATED AT 250 WORDS)

Aging↗
PubMed1992

Hepatic mixed-function oxidases of ferret.

1. Ferret liver mixed-function oxidase enzymes have been quantified using a variety of substrates and the activities have been compared with those found in rat liver. 2. Ferret liver total cytochrome P-450 is only 30% of that of rat liver and exhibits higher 7-ethoxyresorufin O-deethylase (EROD) activity, and lower lauric acid hydroxylase activity than rat liver; other mixed-function oxidases are at similar levels of activity in both species. 3. Induction with 3-methylcholanthrene (MC), similar to MC-induction in rat, increases the total P-450 of ferret liver by 140%, but does not increase P-450 reductase or microsomal protein. EROD specific activity (pmol/min per mg protein) is increased 20-fold by MC treatment. 4. Turnover number of EROD for control liver microsomes of ferret, hamster, mouse, guinea pig and rat were 460, 69, 44, 36 and 35 pmol/min per nmol P-450, respectively, indicating the much higher value for ferret than for any of the rodent species studied. 5. Ferret liver EROD activity is inhibited by the P4501A1 inhibitor, alpha-naphthoflavone. Use of monospecific antibodies in ELISA, Western blot and enzyme-inhibition techniques has shown that EROD activity in ferret liver is attributable to two enzyme proteins orthologous with rat liver cytochromes P4501A1 and 1A2, with the former predominating. MC induces both P4501A enzyme proteins in ferret liver, as in rat liver, with P4501A1 activity predominating.

Animals↗
PubMed1990

Hepatic steatosis during convalescence from influenza B infection in ferrets with postprandial hyperinsulinemia.

The possibility that postprandial hyperinsulinemia could play a role in the development of hepatic lipid disturbances during convalescence from influenza B infection was explored in the ferret as a possible model of the steatosis of Reye's syndrome. Postprandial hyperinsulinemia was produced by feeding young ferrets glucose/water and a regular diet (glucose-treated group), as reflected by the mean serum insulin levels attained, which were 57 and 135 microU/ml during control and postinfluenza periods, respectively. By comparison, ferrets fed water and a regular diet (untreated group) had mean insulin levels of 19 and 22 microU/ml, while postprandial glucose levels were comparable in the two groups of animals for each period. In contrast to untreated animals, grossly visible fatty livers were found in glucose-treated ferrets during convalescence. The total lipid content of these livers had doubled compared with preinfection samples and compared with livers of untreated ferrets. By electron microscopy hepatic mitochondria showed striking changes with diminution of matrix density and reduction in cristae surface area only in convalescent samples from glucose-treated animals. Serum free fatty acid (FFA) levels were considerably higher in the glucose-treated animals during fasting before influenza and also after feeding during convalescence. Serum triglyceride (TG) levels were also high during convalescence in the glucose-treated group. Adipose tissue lipoprotein lipase activities were similar between groups, but hormone-sensitive lipase activity was twelvefold higher in glucose-treated ferrets before and after influenza B. These findings indicate that for a given stimulus, glucose-treated ferrets would mobilize more FFA than untreated ferrets. The total capacity for beta-oxidation of FA by the mitochondrial pathway was identical in all groups of animals. Total carnitine palmitoyl transferase (CPT) activity was the same in both control groups, but was significantly diminished in glucose-treated animals during convalescence. As CPT regulates the entry of FA into the mitochondrial matrix, its reduction in response to higher insulin concentrations would limit the oxidation of FA and stimulate TG accumulation. Therefore, the accumulation of lipid in the liver in this model is regarded to have been caused by the simultaneous occurrence of increased lipolysis and increased hepatic TG synthesis owing, in part, to diversion of activated FA by CPT, which is reduced in activity due to the regulatory action of insulin. These findings may have pathophysiologic relevance for the lipid changes that occur in Reye's syndrome and to fatty liver formation in hyperinsulinemic states.

Adipose Tissue↗
PubMed1990

Large and small airway responses to bronchoconstrictors in the guinea pig and ferret.

In the isolated, perfused lung lobe of the ferret we evaluated the bronchoconstrictor response of its airways to methacholine and histamine, pharmacologic agents associated with the asthmatic state. The bronchus of excised lobes was cannulated and needle scarifications were made on the pleural surface to allow perfusate to exit. Lung airways were perfused at constant flow with equilibrated 95% O2/5% CO2, warmed Krebs-Ringers solution. Perfusion pressure was measured as a gauge of airway resistance. A concentration-dependent smooth muscle contraction of the ferret lung lobes was observed to methacholine and histamine. The ED50's of methacholine and histamine were 6.41 x 10(-6) M +/- 1.38 x 10(-6) (SEM) and 6.41 x 10(-6) M +/- 1.38 x 10(-6) (SEM) and 2.39 x 10(-6) M +/- 0.53 x 10(-6) (SEM), respectively. The maximum level of bronchoconstriction developed in the ferret (2.42 mmHg/ml/min +/- 0.28 SEM (resistance units] in response to methacholine, was six times greater than that found for histamine (0.42 mmHg/ml/min +/- 0.05 SEM). Responses to both agonists were less pronounced in the ferret lung preparation than those in a similar lung preparation of guinea pig. Compliance changes in both animals were also evaluated. The ferret did not demonstrate a compliance change in response to histamine as was seen for methacholine, suggesting that resistance changes precede compliance changes, or that the ferret airways are particularly resistant to histamine. Despite a lesser contractile response, the ferret has the advantage of a relatively large lung and long trachea that allow study in several preparations obtained from a single animal. It should prove a useful animal model for study of pulmonary pharmacology.

Airway Resistance↗
PubMed1992

Helicobacter mustelae isolation from feces of ferrets: evidence to support fecal-oral transmission of a gastric Helicobacter.

Helicobacter mustelae has been isolated from stomachs of ferrets with chronic gastritis and ulcers. When H. mustelae is inoculated orally into H. mustelae-negative ferrets, the animals become colonized and develop gastritis, a significant immune response, and a transient hypochlorhydria. All of these features mimic Helicobacter pylori-induced gastric disease in humans. Because the epidemiology of H. pylori infection is poorly understood and its route of transmission is unknown, the feces of weanling and adult ferrets were cultured for the presence of H. mustelae. H. mustelae was isolated from the feces of 11 of 36 ferrets by using standard helicobacter isolation techniques. H. mustelae was identified by biochemical tests, ultrastructural morphology, reactivity with specific DNA probes, and 16S rRNA sequencing. H. mustelae was not recovered from 20-week-old ferrets which had been H. mustelae positive as weanlings, nor was H. mustelae recovered from 1-year-old ferrets. Isolation of H. mustelae from feces may correspond to periods of transient hypochlorhydria, or H. mustelae may be shed in feces intermittently. The H. mustelae-colonized ferret provides an ideal model for studying the pathogenesis and transmission of H. pylori-induced gastric disease.

Animals↗
PubMed1992

Eosinophilic gastroenteritis with Splendore-Hoeppli material in the ferret (Mustela putorius furo).

Eosinophilic gastroenteritis, focal or diffuse with eosinophilic infiltrations of the stomach or intestine, has been described in human beings, cats, dogs, and horses. In this paper, we describe infiltration of the gastrointestinal tract with eosinophils accompanied by a circulating eosinophilia in six ferrets (Mustela putorius furo). Clinical signs included chronic weight loss, anorexia, and diarrhea. The small intestines from five ferrets had diffuse infiltrates of eosinophils. This resulted in focal or multifocal loss of the muscular tunic in three ferrets. Two of these ferrets also had eosinophilic gastritis. Eosinophilic granulomas with Splendore-Hoeppli material were present in mesenteric lymph nodes in four ferrets. Two ferrets had multiple organ involvement; one had eosinophilic granulomas in the liver, mesentery, and choroid plexus as well as moderate parapancreatic segmental arteritis with infiltration of eosinophils and mural thrombosis. The second ferret had, in addition to moderate diffuse gastric and small intestinal eosinophilic mucosal infiltrations, interstitial eosinophilic pulmonary infiltrates. Examination of all tissues failed to reveal an infectious agent.

Animals↗
PubMed1978

Specific immunity to influenza virus in ferret organ cultures.

Ferret tracheal organ cultures prepared from animals previously infected intranasally with influenza A virus required approximately 130 times more homologous virus (A/PR/8/34(HON1) or A/Port Chalmers/1/73 (H3N2)) to become infected in vitro than similar cultures from normal ferrets. Also, these cultures from convalescent ferrets required 9 times more heterologous virus (A/PR/8/34(HON1) or Sendai) to become infected in vitro than similar cultures from normal animals challenged in vitro with the hererologous virus. We conclude that these tracheal rings are specifically immune. Once tracheal rings are infected, they continue to shed viruses for at least 60 days, the longest period any cultures were kept. Virus sheeding in the intact ferret lasts normally 5-7 days. Thus recovery in the intact ferret seems to be dependent upon factors which are not present, or at least not functional, in the tracheal explant. This is consistent with the hypothesis that recovery is dependent upon systemic rather than local phenomena. Bladder tissue from normal and previously infected ferrets was also cultured and challenged with homologous and heterologous virus. The bladder from previously infected ferrets exhibited specific immunity, although the immunity was more varible.

Animals↗
PubMed1977

The pregnant ferret as a model for studying the congenital effects of influenza virus infection in utero: infection of foetal tissues in organ culture and in vivo.

Organ cultures of ferret foetal tissues showed a similar pattern of susceptibility to influenza virus to that already observed for human foetal tissues (Rosztoczy et al., 1975); respiratory, alimentary and urogenital tissues supported the replication of influenza virus but nervous and lymphopoietic tissues (those which, in man, are associated with foetal or postnatal abnormalities) were insusceptible. In contrast to corresponding human tissues, ferret foetal placenta and amnion readily supported viral replication although both human and ferret umbilical cord were susceptible. In limited experiments, neither the membranes nor the susceptible foetal tissues became infected after intranasal inoculation of pregnant ferrets of various gestational ages. However, after intracardial inoculation of pregnant ferrets with high titre virus (ca 10(9) EBID50) virus was isolated from both foetal membranes and foetuses. The membranes became infected at early, middle and late gestation, but virus appeared to cross the placental barrier to infect foetal tissues only in late gestation. At this stage virus could be isolated not only from those foetal tissues (respiratory, alimentary and urogenital) susceptible in organ culture, but also in small amounts from tissues which were insusceptible in organ culture (heart, lymphopoietic and nervous tissue). Virus was also isolated from foetal membranes and foetuses of late gestation ferrets following intracardial inoculation with a one hundred-fold lower dose of virus which, unlike the higher dose, did not induce a maternal febrile response. The pregnant ferret appears to be a suitable model for investigating the effects on development of foetal infection with influenza virus but it may have disadvantages with regard to the nature and strength of the placental barrier.

Animals↗