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At least 667 records · Page 37Linked to original sources
PubMed1976

The gonadotropic cells in the pituitary of the black molly, Mollienisia latipinna, and other teleosts, identified by the immunofluorescence technique in normal and androgen-treated animals.

Using anti-carp-gonadotropic-gamma-globulin, the indirect immunofluorescence technique was applied to sections of the pituitary of 12 teleost species. From the investigated species, the Poeciliinae, and especially the black molly, showed a distinct localization of fluorescent cells in the mesoadenohypophysis. Strong fluorescence was observed in the ventralmost region, containing the presumed gonadotropic cells; weak fluorescence was observed in the dorsal region, in the presumed thyrotropic cells. The possibility of an unspecific reaction with TSH-cells in the latter region is discussed. Treatment of male black mollies for 38 days with methyltestosterone resulted in a loss of fluorescence in the ventral region of the meso-adenohypophysis, whereas there was no decrease of the fluorescence in the dorsal region. The results support the hypothesis that the ventral basophils in the mesoadenohypophysis produce gonadotropic hormone.

Animals↗
PubMed1976

The lateral recess of the third ventricle in teleosts: an electron microscopic and Golgi study.

The ependyma lining the lateral recess of the third ventricle of the teleost inferior lobe has been studied by light and electron microscopy, including Golgi impregnation methods. As many as five different cell types appear to line the ventricle, but some of these may be similar cells in different stages of activity. One cell type contains small dense-cored vesicles and appears to have processes extending into deeper portions of the lobe. Golgi preparations reveal subependymal cells with apical processes extending to the ventricle and basal extensions which may reach the pial surface. The present observations are discussed in relation to similar studies in other fishes, amphibians and mammals. Possible functions for the various cells observed are suggested.

Animals↗
PubMed1976

The follicular prolactin cells of the primitive teleost engraulis japonica.

The elopiform teleost Engraulis japonica was used for a light and electron microscopical study of the follicle epithelium in the rostral pars distalis of the pituitary. In this species, which has one large follicle in the anterior hypophysis, there is no persistent orohypophysial duct in postmetamorphic stages. The apical pole of the prolactin cells is almost completely overlaid by a surface layer of flattened epithelial cells with a thick glycocalyx. The prolactin cells reach the follicular lumen through "pores" in this cell layer and at the site of the pore the prolactin cells bear unusual specializations consisting of one cilium, several tall microvilli, and a mass of granular material. Prolactin release takes place at the basal pole of the cells.

Animals↗
PubMed1977

Quantitative ultrastructural evidence of alterations in prolactin secretion related to external salinity in a teleost fish (Poecilia latipinna).

Quantitative ultrastructural morphometric studies were made on the prolactin cells of Poecilia latipinna adapted to freshwater (FW), one-third seawater (1/3 SW) and full-strength seawater (SW), and at various times after transfers between 1/3 SW and FW. In fully-adapted fish the rates of prolactin (PRL) synthesis and PRL release are inversely related to environmental salinity. During adaptation to a new salinity the two rates are temporarily uncoordinated, with release increasing or decreasing more readily than synthesis. Synthesis appears to take 30 h or longer to come into balance with the increased release rate following transfer from 1/3 SW to FW, and 72 h or longer to adjust to the reduction in release rate that follows the reverse transfer. The excess PRL granules that accumulate in the latter situation appear to be removed by lysosomal digestion. As in other teleosts, in fish adapted to the external medium the size of the stored PRL granules is inversely related to external salinity, but this relationship breaks down during adaptation to a new salinity. The stellate cells which penetrate between the PRL cells are more prominent, more extensively ramified, and appear more metabolically active in FW-adapted fish than in the other groups. These cells seem to be closely related in function to the secretory activity of the PRL cells.

Adaptation, Physiological↗
PubMed1984

Fine structure of monoamine-containing basal cells in the taste buds on the barbels of three species of teleosts.

The taste buds on the barbels in three species of teleosts (Cyprinus carpio, Misgurnus anguillicaudatus, Parasilurus asotus) were studied by means of fluorescence- and electron microscopy. Intensely yellow-fluorescent cells, which are disk-shaped and located exclusively in a basal position, are observed in the barbel-buds of all fishes examined. The basal cells contain a large number of small clear vesicles approximately 40-60 nm in diameter, which show a tendency to aggregate in the cytoplasm facing the junction of the nerve terminals; chemically transmitting synapses are seen in the latter region. It is suggested from the present observations that the basal cells in the barbel-bud may originate from Schwann cells and have a dual function both as mechanoreceptors and paracrine elements. Since the administration of 5,6-DHT results in an appearance of small dense vesicles among the small clear vesicles, the possibility exists that the basal cell may be capable of taking up monoamines and storing them in the small clear vesicles.

5,6-Dihydroxytryptamine↗
PubMed1984

Ultrastructure and adrenergic innervation of preglomerular arterioles in the euryhaline teleost, Salmo gairdneri.

The opisthonephric kidney of the rainbow trout was investigated by light- and electron microscopy and a fluorescent-histochemical technique for biogenic amines was used. Preglomerular sphincters at the origin of afferent arterioles are present in this euryhaline teleost. The branching point of the afferent arteriole is characterized by (i) the formation of a right angle with the parent vessel, (ii) circularly arranged smooth muscle cells of the tunica media, (iii) additional circularly arranged smooth muscle cells intercalated between endothelium and tunica media, and (iv) a collar-like arrangement of several large endothelial cells with elaborate marginal folds and abundant myoendothelial junctions. A dense adrenergic innervation displaying specific fluorescence was found along the terminal arterioles and afferent arterioles, and conspicuously at the preglomerular sphincters. These results are suggestive of a neural participation in kidney function. They are discussed on the basis of recent evidence from pharmacological and physiological experiments for neural involvement in glomerular intermittency.

Animals↗
PubMed1977

Principal cell types in the pancreatic islet of a teleost fish, Xiphorphorus helleri H.

By means of correlative light and electron microscopy, five pancreatic islet cell categories are described in the teleost fish, Xiphophorus helleri, each of which has specific light microscopic appearance and fine structure. Different histochemical techniques have been used, including immunofluorescence with antiporcine insulin and glucagon sera. In addition to B- and A1-cells, two categories of A2-cells have been observed both reacting with antiporcine glucagon serum: A2-cells with round granules gave a positive reaction for tryptophan; have been observed, both reacting with antiporcine glucagon serum: A2-cells with crystalline granules gave a negative reaction with the same staining technique on the same section. The "clear cells", the last category, were not specifically stained by any of the staining methods carried out in this investigation. The influence of fixation on staining affinities and on ultrastructure was shown to be considerable.

Animals↗
PubMed1980

The structure of the coeliac ganglion of a teleost fish Myoxocephalus scorpius.

In order to compare the structure of a teleost sympathetic ganglion with those of other vertebrates, light, fluorescence histochemical and electron microscopy were carried out on the coeliac ganglion of the scorpion fish, Myoxocephalus scorpius. In common with studies on other vertebrates, fluorescence h istochemistry distinguished two cell types: a) principal neurones which exhibited low levels of specific catecholamine fluorescence and comprise the majority of neurones in the ganglia, and b) smaller intensely fluorescent cells, some of which had processes tens of micrometers long. With the electron microscope, the principal cells were seen to make axodendritic and axosomatic synapses with axons containing mainly 30 nm agranular vesicles at the synaptic site while in other vertebrates usually only one or other synaptic association is present. Both the somata and the processes of intensely fluorescent cells contain 300-600 nm diameter vesicles many of which have electron dense cores. These cells are also innervated by axons containing 30 nm agranular vesicles.

Animals↗
PubMed1979

The mineralization processes in teleost fish scales.

In Teleost fish scales, growth and mineralization are continuous. Different mineralization processes can be distinguished. The external layer of the scale is the first to be mineralized and may be classified as the initial calcifying structure of the scale. The initial calcification loci are matrix vesicles of cellular origin always observed during the formation of this layer. This mineralization process takes place progressively, closely following the elaboration of the organic matrix in the scale periphery. The outer limiting and internal layers of the scale are developed after the external layer has been formed. A mineral substance is deposited without the mediation of matrix vesicles, but in contact with the previously mineralized external layer. This type of mineralization is called subsequential. However, the mineralization of the outer limiting layer closely follows the secretion of a collagen-free organic matrix and is thus different from the mineralization of the internal layer in which the calcification front remains remote from the collagen matrix surface and corresponds to a delayed mineralization process. The isolated calcifications (Mandl's corpuscles) which develop in the unmineralized laminae of the internal layer are mineralized in the absence of matrix vesicles and without making contact with a pre-existing calcified tissue, probably by a heterogeneous nucleation of the collagen fibrils.

Animals↗
PubMed1980

Enameloid in the teleost fish Lophius. An ultrastructural study.

The ultrastructural and chemical differences between mature enameloid and dentine in the teleost fish Lophius were demonstrated using transmission (TEM) and scanning (SEM) electron microscopy, X-ray diffraction analysis, electron diffraction analysis and electron microprobe analysis. An enameloid cap (about 50 micron thick) and a thin layer (1 micron thick) of collar enameloid were revealed in the scanning (SEM) and transmission (TEM) electron microscopes. Collar enameloid, structurally different from dentine both in SEM and TEM, proved to be less mineralized than the cap as revealed by electron microprobe analysis. The enameloid cap was seen to differ from dentine by (i) its electron density in TEM; (ii) the structural arrangement perpendicular to the underlying dentine, observed in SEM and TEM and corroborated by electron diffraction data, which showed a preferred orientation of enameloid crystallites; (iii) its higher F content decreasing gradually from the apex of the tooth to the junction with dentine and falling suddenly below this junction; and (iv) its lower Mg content. Establishment of a classification of enameloids is proposed, similar to that for dentines, in which selachian enameloid would be a reference standard.

Animals↗
PubMed1981

The ultrastructure of the innervation of the intestinal wall in the teleosts Myoxocephalus scorpius and Pleuronectes platessa.

The innervation of the intestinal wall in the teleosts Myoxocephalus and Pleuronectes was examined electron microscopically. Two classes of axons can be identified. The first, which is in the majority, contains numerous 50-150 nm granular vesicles as well as some 40-50 nm agranular vesicles while the second contains predominantly the 40-50 nm agranular vesicles. Chromate/dichromate staining methods suggest that the first type is aminergic. Both types lie in close association with the perikarya of intrinsic myenteric neurons but only axons containing predominantly agranular vesicles have synaptic membrane specialisations. No axon bundles pass into the longitudinal muscle layer in Myoxocephalus gut and though some do in Pleuronectes, they do not closely approach the smooth muscle cells. Axons containing large granular vesicles lie in intimate contact with the myocytes of the circular muscle layer. Both axon types pass through the submucosa to form a plexus underneath the mucosal epithelium. Varicosities containing agranular or granular vesicles are separated from the epithelial cells by a gap of about 200 nm in which lies a basal lamina.

Animals↗
PubMed1979

Fluorescent histochemistry of the teleost gut: evidence for the presence of serotonergic neurones.

The guts of the teleosts Myoxocephalus scorpius, Pleuronectes platessa and Clupea harengus were examined using fluorescent histochemistry and the innervation compared to that in mammals and other lower vertebrates. In Myoxocephalus and Pleuronectes both greeen and yellow fast fading fluorescent nerves were found in the intestine. To test whether the yellow nerves might be serotonergic, an attempt was made to extract 5-HT from the intestine of these fish in a region where enterochromaffin cells were absent. Chromatography of extracts showed the presence of 5-HT, and, in Myoxocephalus, dopamine.

Adrenergic Fibers↗
PubMed1979

Lipid yolk synthesis in a marine teleost, Blennius pholis L.

The site of lipid yolk synthesis in the marine teleost Blennius pholis L. is examined. The relative distributions of cellular organelles and inclusions in the developing oocytes are analysed by morphometric analysis, which indicates that synthesis is probably endogenous occurring in the perinuclear cytoplasm. The role of lipid yolk in this species is discussed.

Animals↗
PubMed1980

Responses of the teleost pituitary (goldfish, eel) to deionized water.

The cytological responses of the pituitary gland during adaptation to deionized water (DW) were investigated in the goldfish and the eel. In both teleost species, a stimulation of the prolactin (PRL) cells could not be detected, although the levels of blood electrolytes (Na+, Ca2+, Cl-) are reduced in the eel. PRL cells appear less active in DW-adapted eels. A striking stimulation of the PAS-positive cells of the pars intermedia occurs in both species after 3 weeks and, in the eel, is still present after 11 weeks. Cell and nuclear hypertrophy, mitoses and a well-developed endoplasmic reticulum are observed. MSH cells are partially degranulated when pigmentation is affected; a reduced activity of MSH cells is evident after 11 weeks. The amount of neurohypophysial tissue is reduced. In the goldfish and the eel, during adaptation to DW, an unknown factor secreted by the PAS-positive cells of the pars intermedia appears to play a more important role than the secretion of PRL. These two species are able to survive in fresh water without the pituitary. The control of the PAS-positive cells by external sodium or calcium is discussed.

Adaptation, Physiological↗
PubMed1980

Vasoactive intestinal polypeptide-like immunoreactivity in nerves of the pancreatic islet of the teleost fish, Gillichthys mirabilis.

In the teleost fish, Gillichthys mirabilis, vasoactive intestinal polypeptide (VIP)-like immunoreactivity is present in some nerve fibres of the principal pancreatic islet and surrounding tissues, the vagus and splanchnic nerves, the coeliac ganglion and the wall of the intestine. The nerves of the pancreatic islet that contain VIP-like immunoreactivity probably correspond to one of the two types of non-cholinergic, non-adrenergic (peptidergic) nerve previously described in this fish. Similarities in the localisation of hormonal peptides in fish and mammals suggest that the regulation of gastroenteropancreatic physiology in fish may resemble that of mammals.

Animals↗
PubMed1980

Lipoprotein crystals in the yolk platelet of a teleost, Pelvicachromis pulcher (Cichlidae).

Yolk-platelt crystals in the oocytes of the teleost Pelvicachromis pulcher (Cichlidae) were shown, using electron diffraction and tilting of thin-sectioned specimens, to possess an orthorhombic lattice with unit-cells sides a = 8.3 nm, b = 16.6 nm and c = 18.0 nm. They thus closely resemble the crystals known for a newt (Triturus sp.) and a frog (Xenopus laevis).

Animals↗
PubMed1976

Changes in the protein metabolism of the CNS of a teleost following stimulation of the lateral-line organ.

Unilateral stimulation of the lateral-line organ (LLO) of the teleost Scardinius erythrophthalmus by current water caused an increase in the afferent fibre activity in the stimulated organ of about 3.5 times as compared with the non-stimulated LLO. There was an increase of [3H] histidine incorporation as compared to controls following stimulation applied either at the beginning (1 h) or at the end (1.5-6 h) of various incorporation times. Following a 1 h stimulation period, the different areas of the LLO-system (lateral nerve, medulla oblongata, cerebellum and valvulae cerebelli), as well as the optic tectum, subtectum and spinal cord showed a significant increase of protein labelling; whereas after 12 h post-incorporation times only the lateral nerve showed highly significant differences as compared to controls. In animals stimulated at the end of a 12 h pre-incorporation period (1.5-6 h) there was a significant increase of protein labelling in all investigated structures of the brain as compared to controls.

Action Potentials↗
PubMed1979

Chloride cells and chloride exchange in the skin of a sea-water teleost, the shanny (Blennius pholis L.).

The fine structure of the skin and its importance in chloride outfluxes were investigated in a sea-water teleost, the shanny (Blennius pholis L.). The epidermis is composed of three cells types: epithelial cells, mucous cells and chloride cells. These chloride cells typically contain a great number of mitochondria and an extensive agranular reticulum extending through the whole cell body. They open at the surface of the epidermis into an apical pit. An undifferentiated small cell is often observed near these chloride cells and probably corresponds to the "adjacent chloride cell". The values of chloride outfluxes through the skin and the gills are respectively 5333+/-884 muEq.h-1.kh-1 and 4479+/-2521 muEq.h-1.kg-1; n = 6; t degrees = 13+/-0.5 degrees C. Thus the ratio between skin chloride outflux and total chloride outflux is 64.7 +/- 9.3%.

Animals↗