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PubMed1982

Fine structural examination of the single heart tube in the fifteen day ferret embryo.

The different segments of the embryonic heart tube of the ferret were examined with light and transmission electron microscopy. The cells of bulbus cordis, bulboventricular junction, primitive ventricle, atrioventricular junction, and primitive atria were in the process of differentiating into myocardial cells. The ventricular muscle cells were the most developed cells; the least mature muscle cells were those located at the arterial and venous ends of the heart tube. The cells between the ventricle and the two ends of the heart tube showed a spectrum of developmental stages, especially with respect to the morphological development of the myofibrils. Other organelles as well as surface specializations did not permit a distinction between cells of the different regions of the heart tube. There was no striking difference in the size and shape of the developing muscle cells of the atrioventricular and bulboventricular junctions compared to the developing ventricular muscle cells. Morphologically there was no evidence to suggest that the tissue of the atrioventricular and bulboventricular rings was specialized or different from any of the other segments of the single heart tube of the embryonic ferret.

Animals↗
PubMed1993

Spike trains and signaling modes of neurons in the ferret lateral geniculate nucleus.

Intracellular recordings were used to examine the action potential firing modes of cells in the ferret lateral geniculate nucleus (LGN) in vitro. We compared the effects of altered membrane voltage on patterns of action potential trains evoked by direct current injection and by retinal afferent (synaptic) stimulation. The results confirm that LGN cells in the ferret can fire action potentials in the "burst" and "tonic" modes that have been described previously for other species. At depolarized membrane potentials, LGN neurons respond to sustained depolarization with short-latency trains of action potentials whose frequency is directly proportional to the amount of current injected. At hyperpolarized membrane potentials, LGN cells enter burst mode, in which depolarizing inputs are differentiated into brief high-frequency discharges whose latency varies with membrane potential. We also observed a "mixed" mode, in which LGN cell responses to synaptic or injected currents within a narrow range of membrane potentials reflect aspects of both burst and tonic firing simultaneously. Thus a striking consequence of the interplay among voltage-dependent membrane conductances in thalamic cells is wide variability in length, duration, and latency of spike discharges elicited by identical stimuli. These results also suggest that the concept that LGN cells display only two active response modes must be expanded to include varying amounts of delay and the possibility of mixed discharges.

Action Potentials↗
PubMed1993

Changes induced in the representation of auditory space in the superior colliculus by rearing ferrets with binocular eyelid suture.

There have been conflicting reports concerning the importance of visual experience in the development of auditory localization mechanisms. We have examined the representation of auditory space in the superior colliculus of adult ferrets that were visually deprived by binocular eyelid suture from postnatal days 25-28, prior to natural eye opening, until the time of recording. This procedure attenuated the transmission of light by a factor of a least 20-25 and blurred the image so that, as long as the eyelids were still fused, the responses of visual units in the superficial layers of the superior colliculus were labile and very poorly tuned. After the eyelids were opened, the representation of the visual field in these layers appeared to be normal. Acoustically responsive units were, as usual, almost exclusively restricted to the deeper layers of the superior colliculus. However, unlike normal animals, where responses occurring only at stimulus onset predominate, most of these units exhibited sustained or multi-peaked discharge patterns. The degree of spatial tuning of individual units recorded from the normal and deprived groups of animals was not significantly different in either azimuth or elevation. Normally orientated maps of both sound azimuth and elevation were also found in the visually deprived ferrets. However, abnormalities were present in the topography and precision of these representations and consequently in their alignment with the overlying visual map. In particular, an increase was observed in the proportion of auditory units with spatially ambiguous receptive fields, in which the maximum response occurred at two distinct locations. These results indicate that patterned visual experience is not required for establishing at least a crude map of auditory space in the superior colliculus, but suggest that it may play a role in refining this representation during development.

Animals↗
PubMed1990

Effects of early monocular deprivation on response properties and afferents of nucleus of the optic tract in the ferret.

Effects of early monocular deprivation on visual response properties of neurons in the nucleus of the optic tract (NOT) were studied in six adult ferrets. Retinal input to NOT was investigated by orthodromic electrical stimulation of optic chiasm and optic nerves. Electrical stimulation of the ipsilateral primary visual cortex was applied to reveal the presence of a cortical pathway to NOT. All 75 neurons studied in the NOT displayed the typical strongly direction-specific response to horizontal stimulus motion; they were activated by ipsiversively directed motion (i.e. motion towards the recorded hemisphere) similar to NOT-cells in animals with normal visual experience. When tested binocularly most of the NOT-cells preferred velocities of 10 or 20 deg/s, revealing no significant difference from animals reared with normal binocular experience. The most pronounced effect of monocular deprivation was observed on ocular dominance: In the hemisphere contralateral to the non-deprived eye, NOT-cells were almost exclusively driven through the contralateral eye. In the hemisphere contralateral to the deprived eye, three of the six animals studied showed a marked dominance of the ipsilateral, non-deprived eye. In the other three animals, most neurons were binocularly activated, but over all they were significantly more strongly activated by the ipsilateral eye than found in normal animals. In four animals, dependence of ocular dominance on stimulus velocity was tested in the NOT contralateral to the deprived eye. In one of them, neurons were almost exclusively driven by the ipsilateral, non-deprived eye, irrespective of stimulus velocity. In the other animals, ocular dominance shifted from contralateral to ipsilateral with increasing stimulus velocities. Electrical stimulation of the optic chiasm revealed a mean latency of 5.53 +/- 0.48 ms. In both hemispheres, NOT-units could only be activated by stimulation of the contralateral optic nerve. Thus, no significant difference in the retinofugal conduction velocities from the deprived and the normal nerve could be detected. Of 52 cells studied, 28 (= 54%) could be activated by stimulation of primary visual cortex, mean latency being 3.9 +/- 1.7 ms. No significant difference in the percentage of cortically excitable cells between the two hemispheres as well as compared to normal animals was found (contralateral to the deprived eye: 67%, contralateral to the non-deprived eye: 53%). Therefore, cortical projections to NOT seem not to be affected by monocular deprivation. The effects of monocular deprivation in the ferret NOT, especially on ocular dominance and cortical input, are compared to the results previously described for the cat.

Afferent Pathways↗
PubMed1979

Probit analysis of the atrioventricular (AV) junctional tissues of the ferret heart.

Probit frequency analysis, a graphic method for determining whether a population is normally distributed, skewed, or multinodal, was used to determine whether P cells are present in different regions of the AV junction in the ferret heart. This analysis indicated that at least 95% of the cells of the transitional zone, superficial AV node, deep AV node, and distal AV bundle of the ferret heart are morphologically homogeneous. In the proximal AV bundle a large cell population is found in addition to the AV bundle cells. The probit analysis was also used to characterize the shape of the cells of each region of the AV junction further. AV nodal cells are not as elongated as the atrial muscle cells and AV bundle cells. These nodal cells also do not branch as extensively as the AV bundle cells.

Animals↗
PubMed1986

An electron microscope study of vagus nerve composition in the ferret.

The total number of axons in the cervical and abdominal vagus nerves of the ferret was counted. The ratio of myelinated to non-myelinated, and afferent to efferent axons was determined. The fibre diameter spectrum of myelinated axons was measured. The total number of axons in the ferret cervical vagus is similar to other mammals (approximately 28,000); the majority of axons are afferent (approx. 24,000) and also the majority of axons are nonmyelinated (approx. 27,000). The dorsal abdominal trunk is about twice the size of the ventral trunk although both trunks have the same number of efferent axons. The abdominal vagal trunks are over 90% afferent.

Afferent Pathways↗
PubMed1992

Activation of two types of fibres in ferret, Mustela putorius furo, cremaster muscle.

Some contractile, histochemical, morphological and electrophysiological properties of ferret, Mustela putorius furo, cremaster muscle have been estimated. Histochemical fibre typing revealed the presence of two types of fibres (type I 66.2%, type II 33.8%). Morphometry performed on ATPase-stained transverse sections showed that type I was composed of a large amount (40%) of small (less than 1400 microns2) cells. In mammalian Ringer two groups of fibres could be recognized on the basis of the values of resting potential (-69.7 mV and -59.1 mV) intracellular sodium activity (8.3 mmol.l-1 and 14.1 mmol.l-1, respectively). In experiments on fibre bundles, the elevation of extracellular potassium concentration to 15-200 mmol.l-1 produced contractures that consisted of a well-defined transient or phasic tension followed by a sustained or tonic tension. Properties of activation and inactivation of the tension analysed in small bundles of cut fibres (lengths 0.5-1.0 cm) were of fast- and slow-twitch type for phasic and tonic phase, respectively. In contrast to the phasic component of K contractures, the tonic phase was abolished by Ca2+ withdrawal and inhibited by Ni2+, Cd2+, Co2+, Gd3+ and gallopamil (D600). In Ca(2+)-free medium the sustained tension was restored by adding Sr2+. It is concluded that in ferret cremaster muscle the presence of slow-twitch fibres would give rise to the tonic component of the K contracture in which an extracellular source of activator Ca2+ is involved. The ability of these fibres to contract with a maintained tension for prolonged periods of time might participate in the temperature regulation of the testes.

Adenosine Triphosphatases↗
PubMed1977

[Psychopharmacological influence on the prey catching behavior of ferrets (Putorius furo L.) (author's transl)].

The prey-catching behavior of ferrets (Putorius furo L.) consists mainly of instinctive behavior patterns, which can be elicited only through their releaser. Then they are performed stereotypically. To get information concerning the central background and the hierarchical structure of this behavior the neuroleptics Haloperidol (0.14 mg/kg), Clozapine (10 mg/kg) and Chlorpromazine (4 mg/kg) were injected i.m. under controlled conditions. In a conditioning experiment the reactivity of the animals was examined. This conditioned reaction was strongly decreased by the drugs. The reaction to the natural stimulus the prey was changed, but not suppressed. The modification of the predatory behavior was manifedsted in an "improvement" of orientation reactions when pursuing the prey and in a better placement of bites. This effect, most evident with Haloperidol, is possibly due to the specific neuroleptic component of the substances. A delay in approaching the prey, or even the total suppression of the prey-catching behavior is suggested to be due to a sedative component which was most obvious in some experiments with Clozapine. On the other hand, there are behavioral elements like the use of paws which are not effected by the neuroleptics. From these and other observations, it is concluded, that the predatory behavior of the ferret has a hierarchically organisated structure. Further it is suggested that some functional connected parts of the behavior have distinct central representation, for they are not influenced in the same way by these drugs.

Animals↗
PubMed1982

Mucous cells of the tracheobronchial tree in the ferret.

Mucosubstances in the tracheobronchial tree of the ferret were studied histochemically. The submucous glands contained predominantly neutral mucins. Scattered between these were cells containing sulphated mucins and sialidase-labile and sialidase-resistant sialomucins. Most of the goblet cells in the trachea, as well as those in the bronchi and larger bronchioles, contained sulphated mucins. A smaller proportion of the goblet cells showed sialidase-labile and sialidase-resistant sialomucins. It will be interesting to see whether ferrets can be used to produce animal models for hypersecretory diseases such as cystic fibrosis and chronic bronchitis.

Animals↗
PubMed1985

Demonstration of immunoglobulin in brains of ferrets inoculated with an SSPE strain of measles virus: use of protein A conjugated to horseradish peroxidase.

Measles virus-specific immunoglobulin G (IgG) has been found in the brains of patients with subacute sclerosing panencephalitis (SSPE), a slowly progressing central nervous system (CNS) disease affecting children. IgG/albumin ratios indicate that the antibodies are probably synthesized in the CNS. In a ferret model system, protein A conjugated to horseradish peroxidase (PrAPx) was used to localize Ig's in brains of animals inoculated with a cell associated strain of SSPE. Ig's were found in plasma cells in various stages of antibody production both in perivascular inflammatory lesions and scattered throughout the cerebral cortex. These findings offer corroborative evidence that the Ig found in SSPE ferret brain and CSF is actively synthesized within the CNS. Antibody was also demonstrated in glial and neuronal cell bodies and processes and in postsynaptic profiles. These are the same sites where measles virus antigens are most frequently found and suggests the possibility of immune complex formation.

Animals↗
PubMed1978

Species variation in the distribution of cholinesterases in the ovary of the plains viscacha, cat, ferret, rabbit, rat, guinea-pig and roe deer.

Sections of ovary from plains viscacha, cat, ferret, rabbit, rat, guinea-pig and roe deer have been histochemically processed to demonstrate acetylcholinesterase (AChE) and butyrylcholinesterase (BuChE) in nervous and non-nervous tissue. The effects of different reproductive states on enzyme activity were observed in some animals. AChE-containing nerves were sparse in rabbit and rat but plentiful in cat and roe deer. Nerves containing BuChE were not detectable in ferret or guinea-pig and were rare in cat. Species variations in the activity and type of enzyme were also found in non-neuronal tissues. Some blood vessels in the ovaries of guinea-pig and viscacha contained AChE. No other species showed a reaction for AChE in non-neuronal stromal tissue but BuChE was present at this site in all animals except rat. Granulosa cells reacted for AChE only in cat and rabbit while luteal cells were reactive in cat, rabbit and roe deer. Some BuChE activity was present in granulosa and or luteal cells in all species except roe deer. In rat, BuChE activity in luteal cells increased during pregnancy and the early phase of pseudopregnancy. The difficulty of assigning a function to ovarian cholinesterases is discussed.

Acetylcholinesterase↗
PubMed1995

Evidence for a projection from the perireticular thalamic nucleus to the dorsal thalamus in the adult rat and ferret.

During early development, the perireticular thalamic nucleus is very large (i.e. has many cells) and has a strong projection to the dorsal thalamus and to the cerebral neocortex. By adulthood, the nucleus has much reduced in size and only a few cells remain. It is not clear whether these perireticular cells that remain into adulthood maintain their connections with the dorsal thalamus and with the neocortex. This study examines this issue by injecting neuronal tracers into various nuclei of the dorsal thalamus (dorsal lateral geniculate nucleus, medial geniculate complex, ventroposteromedial nucleus, lateral posterior nucleus, posterior thalamic nucleus) and into different areas of the neocortex (somatosensory, visual, auditory). After injections of tracer into the individual nuclei of the rat and ferret dorsal thalamus, retrogradely-labelled perireticular cells are seen. In general, after each injection, the retrogradely-labelled perireticular cells lie immediately adjacent to a group of retrogradely-labelled reticular cells. For instance, after injections into the medial geniculate complex, perireticular cells adjacent to the auditory reticular sector are retrogradely-labelled, whilst after an injection into the dorsal lateral geniculate nucleus, retrogradely-labelled perireticular cells adjacent to the visual reticular sector are seen. By contrast, injections of tracer into various areas of the rat and ferret neocortex result in no retrogradely-labelled cells in the perireticular nucleus. Thus, unlike during perinatal development when perireticular cells project to both neocortex and dorsal thalamus, perireticular cells in the adult seem to project to the dorsal thalamus only: the perireticular projection to the neocortex appears to be entirely transient.

Animals↗
PubMed1984

Differential replication of attenuated and virulent influenza viruses in organ cultures of ferret bronchial epithelium. Brief report.

In contrast to its abundant replication in ferret nasal epithelium in vivo and in vitro, comparable to that of the virulent strains, the attenuated influenza virus A/PR/8/34 produced much lower yields than the virulent strains in organ cultures of bronchial epithelium agreeing with its relative inability to infect the lower respiratory tract of ferrets. The replication of another attenuated strain showed different temperature characteristics in bronchial epithelium to that in nasal turbinate epithelium.

Animals↗
PubMed1985

Recent H1N1 viruses (A/USSR/90/77, A/Fiji/15899/83, A/Firenze/13/83) replicate poorly in ferret bronchial epithelium. Brief report.

Three recent wild-type H1N1 influenza virus isolates (A/USSR/90/77, A/Fiji/15899/83 and A/Firenze/13/83) replicated poorly in organ cultures of ferret bronchial tissue compared with the replication of an H3N2 wild-type virus (A/England/939/69). All four viruses replicated well in nasal turbinate tissue. Examination of one H1N1 virus (A/USSR/90/77) in vivo showed heavy infection in the upper respiratory tract of ferrets but little in the lower respiratory tract. These results raise the possibility that the mildness of human influenza arising from the H1N1 strains may be due to lack of capacity to attack the lower respiratory tract as well as the presence of antibody in previously exposed persons.

Animals↗
PubMed1985

Measurement and stoichiometry of bumetanide-sensitive (2Na:1K:3Cl) cotransport in ferret red cells.

The bumetanide-sensitive uptake of Na+, K+(Rb+) and Cl- has been measured at 21 degrees C in ferret red cells treated with (SITS + DIDS) to minimize anion flux via capnophorin (Band 3). During the time course of the influx experiments tracer uptake was a first-order rate process. At normal levels of external Na+ (150 mM) the bumetanide-sensitive uptake of K+ was dependent on Cl- and represented almost all of the K+ uptake, the residual flux demonstrating linear concentration dependence. The uptake of Na+ and Cl- was only partially inhibited by bumetanide indicating that pathways other than (Na + K + Cl) cotransport participate in these fluxes. The diuretic-sensitive uptake of Na+ or Cl- was, however, abolished by the removal of K+ or the complementary ion indicating that bumetanide-sensitive fluxes of Na+, K+ and Cl- are closely coupled. At very low levels of [Na]o (less than 5 mM) K+ influx demonstrated complex kinetics, and there was evidence of the unmasking of a bumetanide-sensitive Na+-independent K+ transport pathway. The stoichiometry of bumetanide-sensitive tracer uptake was 2Na:1K:3Cl both in cells suspended in a low and a high K+-containing medium. The bumetanide-sensitive flux was markedly reduced by ATP depletion. We conclude that a bumetanide-sensitive cotransport of (2Na:1K:3Cl) occurs as an electroneutral complex across the ferret red cell membrane.

4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid↗
PubMed1995

Rabbit and ferret parietal cell inhibition by Helicobacter species.

We tested sonicates of Helicobacter pylori, H. mustelae, and H. felis for inhibition of acid secretion in rabbit and ferret isolated gastric glands. Three H. pylori strains, two of three H. mustelae strains, and two H. felis strains significantly inhibited acid secretion in rabbit cells by 95.2-93.3%, 55.9% and 96.4%, and 83.4-96%, respectively. All Helicobacter strains examined inhibited acid secretion by ferret cells by 65.3-76.8%, 89.1-97.6%, and 85.8-92.8%. H. pylori inhibited acid secretion after stimulation with histamine and isobutylmethylxanthine or with 8-bromo-cyclic adenosine monophosphate (P < 0.05 for all tests). These findings demonstrate that acid inhibition is a property common to the three Helicobacter species tested. It occurs independently of the mammalian origin of the parietal cell, and it does not involve blockade of histamine-2 receptors.

1-Methyl-3-isobutylxanthine↗
PubMed1996

Estrogenic control of preoptic area development in a carnivore, the ferret.

1. Evidence is reviewed which shows that a sexually dimorphic nucleus located in the dorsomedial portion of the male ferret's preoptic area/anterior hypothalamus (POA/AH), called the male nucleus of the POA/AH (Mn-POA/AH), develops during fetal life in response to the action of estradiol, which is formed directly in the nervous system from circulating testosterone over the final quarter of a 41-day gestation. 2. Results are summarized which establish that neurons which make up the Mn-POA/AH are born prior to the critical period of estradiol's action in the male brain. Other data show that some radial glial processes, visualized immunocytochemically using antibodies against GFAP, emanate from proliferative zones at the base of the lateral ventricles in a dorsal-ventral orientation, whereas other glial processes emanate laterally from proliferative zones lining the third ventricle. 3. We suggest that at least some neurons which constitute the dorsomedial POA/AH are born in proliferative zones surrounding the lateral ventricles, raising the question of whether estradiol acts in developing males to influence the migration of these neurons along radial glial guides into the Mn-POA/AH. 4. Finally, evidence is summarized showing that excitotoxic lesions of the dorsomedial POA/AH enhance males' preference to approach and interact with another sexually active male, as opposed to an estrous female, when adult subjects are castrated and treated with estradiol benzoate. These data suggest that the sexually dimorphic Mn-POA/AH is an essential part of a CNS circuit which determines heterosexual partner preference in the male ferret.

Animals↗
PubMed1989

Electromechanical effects of leukotriene D4 on ferret tracheal muscle and its muscarinic responsiveness.

We investigated the possible electrophysiological processes by which leukotriene D4 (LTD4) affects airway smooth muscle and its responsiveness to acetylcholine (ACh). For study in vitro, preparations of ferret tracheal muscle (dissected free of overlying mucosal and submucosal layers) were used. These preparations were arranged so that force transducers and glass intracellular microelectrodes (having tip resistances of 35-60 megohm) could be used to measure isometric force generation and cell membrane potential (Em) simultaneously from muscle stimulated by LTD4. At rest, the muscle was electrically and mechanically quiescent and had an Em of -59 +/- 0.2 mV (mean +/- SEM). We found that ferret tracheal muscle cells were relatively sensitive to LTD4, and that both the resulting depolarization (beginning at 10(-10) M LTD4) and force generation (produced by higher concentrations) progressed in a concentration-dependent manner. Depolarization by 10(-9) M LTD4 elicited electrical oscillations. These oscillations were accompanied by phasic contractile activity at 5 x 10(-9) M LTD4. Verapamil abolished these oscillations and diminished force substantially. We also found that ACh depolarized and contracted the muscle in a concentration-dependent manner. It caused electrical oscillations at greater than or equal to 10(-6) M. Diltiazem abolished these oscillations and markedly diminished force generation without affecting Em. Preexposure of airway muscle preparations for 20 min to a concentration (10(-10) M) of LTD4 that, by itself, did not produce significant force, substantially augmented the voltage-tension relationship of the muscle upon ACh stimulation. We conclude that there is an electrical basis for the slow, prolonged force generation of airway muscle caused by LTD4, and that LTD4 potentiates the electromechanical responsiveness of the airway muscle to muscarinic stimulation.

Acetylcholine↗