PubMed Health⌕ Search

Biomedical subjects

A G Sathyanesan

Publications and source records attributed to A G Sathyanesan.

At least 19 recordsLinked to original sources
PubMed1979

A histoenzymological study of the saccus vasculosus of the freshwater teleost, Clarias batrachus (L.).

The saccus vasculosus (SV) of C. batrachus is comparatively small and situated latero-dorsal to the pituitary in between the lobi inferiores. It is in open communication with the third ventricle and is made up of coronet and supporting glial cells with interspersed liquor contacting neurons. These cellular constituents are arranged in one to three layers which are not thrown into folds. The PAS positive nature of the apical part of some coronet cells and their continuation with the PAS and AF positive material present in the lumen strongly suggest their secretory role. The coronet cells exhibited strong NADH diaphorase, NADPH diaphorase, cytochrome oxidase and MAO activity. AChE activity was comparatively weak. These enzyme histochemical studies show that SV has a dual function of transport and secretion. The strong MAO activity suggests the probable aminergic control of this organ.

Acetylcholinesterase↗
PubMed1979

Functional cytology of the pituitary gland of the teleost Clarias batrachus (L.).

The RPD (rostral pars distalis) is formed of two cell types. The erythrosinophilic acidophils were hypertrophied in response to ammonium sulphate treatment and dark background adaptation. The response to former may be due to osmoregulatory involvement. The PbH positive corticotrophs were markedly hypertrophied and degranulated in response to metopirone and ammonium sulphate treatments. They were moderately activated in the dark and white background adapted fish. The PPD (proximal pars distalis) is composed of two types of cyanophils and acidophils. The thyrotrophs are identified by their hypertrophic response to radiothyroidectomy and thiourea treatment. They are distributed in the ventral part of the PPD, posterior neurohypophysis and PI (pars intermedia). The gonadotrophs which largely occupy the dorsal aspect of the PPD increase numerically as the gonads mature and become the major cell type before spawning. The acidophilic somatotrophs are distributed all over the PPD. They are the predominant cell type in the PPD of fish with immature gonads. They gave strong reaction to Baker's acid haematein indicating the presence of phospholipid. Both PbH and PAS cells of PI were stimulated in fish kept in dark background whereas they did not exhibit any obvious change under white background adaptation.

Animals↗
PubMed1978

An enzymecytochemical study on the adrenal of the freshwater teleost, Clarias batrachus (L.).

The adrenal homologue of C. batrachus is distributed around the postcardinal vein in the pronephric head kidney. The cortical cells are round or oval in shape. They showed positive reaction for total lipid, glycogen and ascorbic acid. Their intense delta5-3beta HSDH activity indicates their capacity for steroid biosynthesis. In addition, the cortical cells of C. batrachus exhibited strong G-6-PD, NADPH diaphorase, NADH diaphorase, MAO and weak SDH and LDH activity. The presence of MAO suggests the aminergic control of the adrenal in this species and the silver positive fibres seen the cortical cells were hypertrophied, degranulated and the lipid content was also decreased. The chromaffin or medullary cells were distributed in groups among the cortical cells. They are largely oval or angular in shape. They react positively to ferric ferricyanide, chromaffin and argentaffin reactions and ascorbic acid test.

3-Hydroxysteroid Dehydrogenases↗
PubMed1978

A micromorphological and histoenzymological study on the third ventricular ependyma of the teleost Clarias batrachus (L.).

The circum ventricular region of C. batrachus is highly vascular and the ependymal cells appear differently when stained with haematoxylin, silver impregnation and Golgi-Cox techniques. The ventricule has PAS and AF positive material and some ependymal cells themselves are PAS positive. Few AF positive peptidergic and several AF negative small neurons have liquor contacting terminals. Golgi-Cox preparations reveal a variety of forms among the tanycytes. Their basal processes which are barbed or studded with varicosities, usually end on blood vessels and other neuronal elements. These basal processes themselves are often seen in direct morphological contact. Smaller silver positive cells without basal processes are also evident. Some tanycytes have apical processes resembling broadened endfeet. Few neurosecretory tracts are Golgi-Cox positive and can be differentiated from the tanycytic processes by their smooth surface. Varying degrees of ascorbic acid activity are noticed inside the ventricle, among the tanycytes and in the neurons of the NLT. Some of the latter neurons have liquor contacting terminals as well. The ChE activity noticed in some parts of the ependyma and in some NLT cells suggest their probable differential cholinergic control. Presence of SDH, NADPH and NADH diaphorases and cytochrome oxidase in varying quantities in the ependymal cells suggests that they are metabolically active. Presence of MAO positive tracts bridging the subependyma and ventricle suggests the degradation of monoamines at these sites. The presence of various enzymes and the morphological relationship of the tanycytes described in this species are comparable to those of the mammals. It is significant as this species is reported to have a median eminence morphologically resembling the tetrapods.

Animals↗
PubMed1978

Hypothalamo-hypophysial vascularization of the teleost, Puntius sophore (Ham.) with special reference to its tetrapodan features.

In Puntis sophore a hypothalamo-hypophysical portal system structurally comparable to the tetrapods is present. Apart from this the teleostean type of neuroadeno-interface vasculature is also evident. The hypothalamic artery gives rise to the primary capillary plexus of the infundibular floow. The protal vessels formed from them largely irrigate the adenohypophysis through their secondary vascular network. The dense neurosecretory axonal ramifications present in the infundibular floor are in close morphological contact with the primary plexus. This region also exhibits intense monoamine oxidase activity. Thus, the infundibular floor of P. sophore is structually comparable to the meidan eminence of the higher vertebrates.

Animals↗
PubMed1978

Cytochemical and histoenzymological studies on the adrenal of the teleost, Puntius sophore (Ham.).

In Puntius sophore the adrenal tissue is situated in the pronephric head kidney. The medullary cells are arranged closely around the wall of the cardinal veins and their branches. The cortical cells are located around the medullary cells in several layers forming a large mass of tissue. With the aid of chromaffin reaction techniques the medullary cells were differentiated. Noradrenaline cells were identified with iodate reaction technique. Cortical cells gave positive reaction to cholesterol, lipid, phospholipid and ascorbic acid tests. The steroidogenic property of these cells is suggested by the presence of delta 5 3 beta HSDH, G-6-PD and 11 beta HSDH enzymes. The intense MAO activity which is reported largely in the cortical tissue of Puntius sophore is not well known in the fishes.

Adrenal Glands↗
PubMed1977

Hypothalamo-hypophysial neurosecretory and vascular system of the teleost Labeo rohita (Ham.).

The paired nucleus preopticus (NPO) lying on either side of the III ventricle gives rise to the left and right main neurosecretory tracts which proceed posteroventrally towards the pituitary and give rise to several finer axons which ramify the infundibular floor adjacent to the pituitary. The bulk of the neurosecretory tracts enter the pars intermedia and few finer ones are seen among the pars distalis. The ventromedian component of the nucleus lateralis tuberis (NLT) is aldehyde fuchsin (AF) positive whereas the anterolateral neurons are AF negative. The internal carotid artery gives rise to the hypophysial and ventral hypothalamic arteries. The ventral hypothalamic artery gives rise to the primary capillary plexus at the infundibular floor region adjacent to the pituitary stalk. Portal vessels formed from this plexus largely irrigate the adenohypophysis. The hypophysial artery enters the neurohypophysis and gives rise to typical teleostean type neuradenointerface vasculature. Morphological contact between the neurosecretory axons and primary capillary plexus at the floor of the infundibulum suggests the possibility of at least some active principles entering the blood vessels. Structurally L. rohita exhibited both tetrapodean and teleostean type of hypothalamo-hypophysial vasculature. Morphological evidences suggest a direct neuroglandular and an indirect neurovasculoglandular pathways of hypothalamic control of hypophysis in L. rohita.

Animals↗
PubMed1977

Pituitary cytology of the Indian carp Labeo rohita (Ham.).

In the adenohypophysis of Labeo rohita eight cell types could be identified on the basis of their different tinctorial response to various staining techniques. The rostral pars distalis has 3 types of cells. Type 1 is stained with erythrosin, orange G, and acid fuchsin. Type 2 cells are lead hematoxylin positive and give an amphiphilic reaction in response to tri and tetrachrome techniques. Type 3 cells are stainable with PAS, ATh, AB, AF, and aniline blue and are distributed in an area comprises of anteroventral RPD and anterodorsal PPD. Apart from type 3, the PPD has two more cell types. The classical acidophils forming the type 4 cells readily take up orange G, erythrosin and acid fuchsin. Type 5 cells have affinity for PAS, ATh, AB, AF and aniline blue as that of type 3 cells, but they are relatively smaller. Pars intermedia has type 6 and 7 cells which are PbH and lightly PAS + ve respectively. Eight cell type is constituted by the chromophobes which are seen in all the components of the adenohypophysis, they might be the immature or degranulated chromophils. On the basis of colour reactions cell types 1, 2, 3, 4 and 5 of Labeo rohita are comparable to the prolactin, ACTH, TSH, STH and gonadotropin secreting cells described in other teleosts by earlier workers using comparable techniques. However, functional interpretation based on staining reactions is tentative and needs experimental verification.

Animals↗
PubMed1976

Distribution of monoamine oxidase (MAO) in relation to the hypothalamo-hypophyseal system of the teleost Clarias batrachus (L.).

Varying degrees of monoamine oxidase (MAO) activity were noticed all along the hypothalamo-hypophyseal neurosecretory tract in C. batrachus. Intense activity was evident on the wall of the secretory cells of the adenohypophysis, neurons of the nucleus preopticus (NPO) and nucleus lateralis tuberis (NLT). However, MAO activity was also observed in the cytoplasm of some neurons in the ventromedian region of the NLT and groups of cells present in the neurohypophyseal ramifications of the pars intermedia. A strong accumulation of formazan granules in the median eminence (ME) and the neuroadeno interface lends further support to the view that C. batrachus has a ME of both the tetrapodan and the teleostean type. The distributional pattern of MAO in the hypothalamus and hypophysis suggests that monoaminergic fibres are probably involved in the secretory mechanism of the releasing factors and pituitary hormones.

Animals↗
PubMed1975

Relationship between the preoptico hypophysial system and the vascular system in the teleost Rita rita (Ham.).

In Rita rita the internal carotid artery gives rise to hypothalamic and hypophysial arteries. The hypophysial artery directly enters the pituitary and largely contributes to the interface vasculature lying in between the neurohypophysis and the pars distalis which can be considered as an equivalent of the median eminence. Blood vessels from the interface vasculature enter the pars distalis. The hypothalamic artery gives rise to the primary capillary plexus in the infundibular floor and the portal vessels formed by it irrigate the glandular pituitary. Both, at the level of the hypothalamus and at the interface, neurosecretory material might get access to blood vessels. Thus, in Rita rita, not only the typical teleostean type of hypothalamo-hypophysial vascularization is present, but also an incipient tetrapodal pattern is evident.

Animals↗
PubMed1975

Antagonistic response of chlorpromazine and formalin in effecting quantitative changes in the neurosecretory material in the teleost Clarias batrachus (L.).

The hypothalamoneurohypophysial complex of Clarias batrachus maintains an appreciable quantity of neurosecretory material (NSM) under normal conditions. Stress caused by the injection of formalin depletes 70-90% of the stainable NSM from all the component parts of the neurosecretory system, namely the nucleus preopticus (NPO) the neurosecretory tract, and the neurohypophysis. Formalin apparently releases the NSM and stimulates the neurons of the NPO. Chlorpromazine (CPZ) treatment seems to cause quantitative increase of NSM throughout the neurosecretory complex. Simultaneous injection of CPZ and formalin showed that the formalin-induced depletion of NSM could be inhibited by CPZ.

Animals↗
PubMed1975

Hypothalamohypophysial vascular and neurosecretory link in the teleost Bagarius bagarius (Ham.).

A three-dimensional picture of the hypothalamohypophysial neurosecretory system of B. bargarius could be obtained by adopting in situ staining techniques. The paired NPO give rise to left and right neurosecretory tracts which, although they approximate as a common tract, maintain their individuality till entering the pars intermedia. The ventral hypothalamic and the hypophysial arteries take their origin from the internal carotid artery. The former contributes to the formation of the primary plexus of the median eminence and the latter enters the pituitary directly, giving rise to the neuroadreno-interface vasculature. The vasculature of the median eminence lies in close contact with the long common neurosecretory tract. Morphological evidence suggests that in B. bagarius there are three pathways of hypothalamic control of the hypophysis: (1) A direct neuroglandular pathway, where the neurosecretory axons come directly in contact with the adrenohypophysial cells. (2) An indirect neurovasculoglandular pathway, where the blood exposed to the NSM at the median eminence comes in contact with gland cells. (3) Another indirect neurovasculoglandular pathway, where the blood is exposed to NSM at the neurohypophysis prior coming in contact with the gland cells. Thus, B. bagarius has the 'median eminence equivalent' neuroadeno-interface vasculature typical of the teleosts and the median eminence comparable to the Elasmobranchs, Holocephali and primitive Actinopterygians. This shows that the pituitary portal system of teleosts is in general agreement with that of other fish groups, except that in some it is restricted to the neuroadreno-interface, whereas in others like B. bagarius it extends to the hypothalamus also. These may be termed anterior and posterior median eminence.

Animals↗
PubMed1975

Alcohol inhibition of formalin induced depletion of neurosecretory material in the teleost Clarias batrachus (L).

In the normal C. batrachus a fair amount of stainable neurosecretory material (NSM) is always present in all the component parts of the hypothalamo-neurohypophysial (HN) complex. When formalin was injected intraperitoneally 70 to 90% of the NSM was depleted from the HN complex. When ethyl alcohol was administered immediately after formalin treatment, the depletion of NSM was inhibited, and their staining intensity could be compared with those of untreated controls.

Animals↗