Effects of metopirone on the structure of endocrine glands in the male lizard,Cnemidophorus l. lemniscatus (L.)

Summary Adrenals, pituitary glands, thyroids, testes and kidneys of metopirone-treated and control male lizards were studied by light microscopy. Pituitary-interrenal axis: A great hypertrophy and hyperplasia of the interrenal cells and the pituitary corticotrophs were found in the experimental group. Pituitary-thyroid axis: Metopirone-treated animals showed a moderate hypertrophy and degranulation of pituitary thyrotrophs, and signs of uneven hyperactivity of the thyroid. Pituitary-testicular axis: By effect of metopirone, a marked regression of pituitary interstitiotrophs and a virtual disappearance of the testicular interstitial gland took place. The second portion of the kidney sexual segments appeared degranulated as in castrated animals. The pituitary folliculotrophs and the seminiferous epithelium of the testis did not show alterations.     

Seasonal variations in the cyanophils of the pituitary gland in correlation with reproductive cycle of Channa striatus (Bloch)

Seasonal changes in the cyanophils of the proximal pars distalis of the pituitary gland of C. striatus are conspicuous, and they closely follow the reproductive cycle. There is a poor concentration of their glycoproteinaceous contents during the resting phase and higher concentration during the maturation phase. The cyanophils also undergo a process of hypertrophy, granulation, followed by degranulation and vacuolisation during the spawning phase. They almost empty their contents during the post-spawning period.     

A histological study of the hypophysial-gonadal system during sexual maturation and spawning in the milkfish, Chanos chanos (Forskal)

The pituitary gland of the milkfish, Chanos chanos , was studied at different stages of sexual maturation and spawning. Consecutive median sagittal sections were treated with a range of stains to demonstrate the different cell types and regions. The milkfish pituitary consists of a neural component, the neurohypophysis, and an epithelial component, the adenohypophysis, which in turn consists of three regions: the rostral pars distalis (RPD), proximal pars distalis (PPD), and pars intermedia (PI). However, unlike most teleosts, the pituitary gland of the milkfish is encased in a bony chamber, has dorsal and ventral lobes and extends anteriorly from its point of origin at the base of the brain. PAS (+) basophils are found in all regions of the adenohypophysis, but mostly in the proximal pars distalis. These cells undergo hypertrophy and hyperplasia during sexual maturation, shrinkage and degranulation during spawning.     

Cyclic changes in the pituitary gland in correlation with the testicular cycle in a hill-stream teleost, Schizothorax richardsonii (Gray and Hard).

In Schizothorax richardsonii, the pituitary gland has been studied in correlation with the phases of the testicular cycle. The cyanophils of the proximal pars distalis show hypertrophy, hyperplasia, granulation, degranulation and vacuolisation in concurrence with the spermatogenic cycle. Secretory activity of the cyanophils controls the maturation of testes, which indicates that these cyanophils are gonadotrops. The formation of sperm mother cells, however, does not appear to depend on the secretory activity of the pituitary. During spawning and regression phases, the azocarminophilous granules in the cytoplasm of the cyanophils show quantitative variation. The migratory chromophil cells show numerical variation, suggesting their involvement in the reproductive cycle. Neurosecretory material also appears to play some part in reproduction.     

Immunocytochemical studies of the gonadotropic cells in the pituitary gland of male mullet, Mugil cephalus, during the annual reproductive cycle in both natural habitat and captivity

Using antiserum specific for the β subunit of coho salmon gonadotropic hormone II (GTH II), an immunocytochemical study of Mugil cephalus (L.) pituitaries was conducted during the annual reproductive cycle of the male in both natural habitat and captivity. The gonadotropic potency of the pituitary gland in general underwent an obvious increase during testicular development, reaching a peak at the time of reproductive maturity. During the testicular cycle of M. cephalus, the GTH cells showed an increase in immunoreactive staining intensity, granulation, hypertrophy and hyperplasia during sexual maturation. However, degranulation, vacuolization, and weakened immunoreactivity of these cells occurred during spawning. The GTH cells in the pituitary gland of M. cephalus males reared in captivity appeared with high synthetic and secretory activity but the reproductive activity declined, as reflected in the form of low values of the gonadosomatic index (GSI) and earlier resorption of the testes.     

Changes in the Pituitary-interrenal Axis after Gonadectomy in the Catfish,Clarias batrachus (Linn.)

The effects of gonadectomy on the cytological structure of the hypophysis and interrenal tissue of Clarias batrachus have been investigated. Forty days after gonadectomy remarkable hypertrophy of certain cyanophils, identified later as gonadotrops, has been observed followed by hyperplasia. The somatotrops also seem to undergo similar changes, and as a result the proximal pars distalis (PPD) increases enormously and encroaches upon the pars intermedia (PI). The gonadotrops undergo a gradual degranulation and become devoid of stainable cytoplasm by 90 days. No signet ring cells have been noticed at any stage. The cyanophils in the ventral region of the PPD, identified as thyrotrops, also show degranulation, but to a comparatively limited degree. The ACTH cells undergo gradual hypertrophy and degranulation. A progressive increase is noticed in the nuclear diameter. The interrenal cells are activated as indicated by the enhanced nuclear indices. It is suggested that a fall in gonadal steroids may result in ACTH release which in turn activates the interrenal cells.     

Histophysiology of the pituitary gland in correlation with the ovarian cycle in Tor (Barbus) tor (Ham.)

Summary The histophysiology of the pituitary gland has been studied in correlation with the phases of the ovarian cycle in Tor (Barbus) tor. The cyanophilic cells in the proximal pars distalis display changes related to stages in the maturation of the ovary. The cyanophils, which display hypertrophy and hyperplasia and undergo degranulation and vacuolation during maturation, prespawning, and spawning periods, are identified as gonadotrops. Apparently their glycoproteinaceous contents, gonadotropin(s), control the processes of vitellogenesis, ovarian maturation, and initiation of oviposition. Depletion of glycoproteinaceous contents in these cyanophils leads to atresia of oocytes at advanced stages, but it does not appear to interfere with oogonial proliferation. The neurosecretory materials are implicated in female reproduction.I am deeply indebted to Professor H. Swarup for suggesting and supervising this study and to Dr. Grace E. Pickford for her generosity in sending me xerox copies of some articles.     

The vascular architecture of the developing organum vasculosum of the lamina terminalis (OVLT) in the rat

The pituitary gland of the red grouper, Epinephelus akaara, was studied by histochemical techniques, and the prolactin cells, corticotrops, somatotrops, gonadotrops, thyrotrops, pars intermedia cells and neurohypophyseal cells, were identified. Oestradiol-17 beta treatment caused PAS-positive cells in the proximal pars distalis, presumably a mixture of gonadotrops and thyrotrops, to undergo hypertrophy, vacuolation and degranulation of cytoplasmic glycoprotein granules. Disappearance of cytoplasmic granules was also evident in the PAS-positive pars intermedia cells. Oestrogen-treated fish also showed an increase in the hepatosomatic index, and hepatocytes enlarged in size, their nuclear diameter increased and large vacuoles were formed in the cytoplasm. These changes in the liver were paralleled by a secretion of vitellogenin into the serum and an increased production of mucus by the thickened skin epithelium. Testosterone injections did not affect such changes, neither in the pituitary nor liver cells, but a proliferation of skin epithelial cells was noted. Neither oestradiol-17 beta nor testosterone stimulated ovarian incorporation of vitellogenin, but treatment with high doses (5 mg/kg) of oestradiol-17 beta or testosterone brought about a slight increase in the gonadosomatic index and atresia of some of the primary oocytes. The oogonial population size decreased in response to treatment with high doses of oestradiol-17 beta.     

Hypothalamic lesions stimulating growth hormone cell activity in the goldfish

Summary The cytology of the growth-hormone (GH) cells of the goldfish pituitary were examined following electrothermic lesions of the anterior praeoptic hypothalamus and telencephalon. Following lesions of the nucleus preopticus (NPO) light microscopy of the pituitary revealed a significant increase in the nuclear diameter and a degranulation of the GH cells. Lesions of the telencephalon anterior or dorsal to the NPO had no cytological effect on the GH cells. The ultrastructural appearance of the GH cells of NPO-lesioned fish was characterized by a marked degranulation of the cytoplasm and a proliferation of the rough endoplasmic reticulum indicative of enhanced secretory activity. The GH cells of the proximal pars distalis (PPD) are directly innervated by peptidergic (type A) and aminergic-like (type B) neurosecretory axons. Following lesions of the NPO, there was a marked reduction in the number of type A fibers in the PPD. These results suggest that the type A fibers innervating the GH cells originate in the NPO and act to inhibit the secretory activity of the GH cells.     

鳗鲡繁殖生物学研究Ⅳ．人工催熟过程中下海鳗鲡的GtH分泌活动、性腺发育状况和脑垂体GtH细胞的超显微结构

雌二醇通过正反馈作用能促进脑垂体促性腺激素(GtH)细胞的合成活动,使脑垂体GtH水平显著升高。促黄体素释放激素的类似物(LHRH-A)和利血平(reserpine,RES)能促进脑垂体GtH细胞的分泌活动,使血液中GtH含量显著升高。鲤垂体、人体绒毛膜促性腺激素(HCG)和LHRH—A三种激素混合进行多次注射能诱导雌雄鳗鲡性腺发育成熟,其催熟效果明显优于它们的分别单独多次注射或者鲤鱼脑垂体和HCG的多次注射,表明外源的和内源的促性腺激素对于诱导鳗鲡性腺发育成熟都是重要的。鳗鲡脑垂体GtH细胞超显微结构的观察证实它们在激素诱导性腺发育成熟过程中处于活跃的合成与分泌状态。     

Effect of hypocalcemic and hypercalcemic substances on the parathyroid histology of the lizard, Uromastix hardwickii (Gray).

The effects of hypocalcemic and hypercalcemic substance on activity of the parathyroid and plasma calcium and phosphorus levels in the lizard, Uromastix hardwickii are described. The cellular hypertrophy and degranulation of cytoplasm in the parathyroid cells along with decrease in plasma calcium level appeared after sodium citrate and ethylenediaminetetraacetate (EDTA) treatment. On the other hand, degenerative changes are observed after calcium chloride treatment. It is suggested that the secretion of parathyroid is regulated by the circulating blood calcium level.     

Influence of high ambient temperature on the reproductive function of the male rat

An attempt was made to determine the extent to which an inhibition of testicular androgen production by high ambient temperature may explain the damaging effect of heat on spermatogenesis, using male albino rats. Spermatogenesis and androgen synthesis were affected by high heat in the intact rat and in the hypophysectomized rat maintained on pituitary gonadotrophins or testosterone propionate. Heat treatment decreased the weight of the ventral prostate to half that of the control. High ambient temperatures did not severely damage testosterone-maintained spermatogenesis in hypophysectomized rats. Heat treatment did not lead to remarkable changes in the ultrastructure of the gonadotrophic cells of the anterior pituitary gland although there was a generalized and partial degranulation of anterior pituitary cells.     

Hypertrophic changes in the ovarian chromaffin tissue (catechol storing tissue) under the influence of the pituitary and its theoretical implications in the teleost fish, Nandus nandus.

Evidence is presented in this work for the existence of a special chromaffin tissue in the ovary of the percoid teleost fish, Nandus and its hypertrophy under the influence of the pituitary extracts. The relationship between the pituitary and the ovary has been discussed from various viewpoints and the secretions of the ovarian chromaffin tissue and the interrenal are suggested as the possible mediators in the process of maturation and ovulation in the teleost fishes.     

The mechanism of liver splanchnomegaly produced by a transplantable pituitary mammotropic tumor in rats.

The mechanism of liver splanchnomegaly developed in rats bearing a transplantable pituitary mammotropic tumor which secretes large amounts of ACTH and prolactin has been studied. The results indicate that in the first phase of tumor growth liver enlargement could be due to hypertrophy, and later mainly to hyperplasia which overcomes hypertrophy. The adrenal glands were found to play an essential role in the process of liver splanchnomegaly because adrenalectomy prevented the disproportional growth of the liver. Evidence is presented showing that glucocorticoids are the dominant hormones responsible for the development of liver splanchnomegaly.     

Changes in the nucleoli of epithelial cells of the kidney tubules in mercuric chloride-induced experimental kidney tubular necrosis

Electron-microscopic studies of epithelial cells of uric tubules in white rat kidneys after i.m. injections of mercury dichloride (0.4 mg/100 of body weight) given every 24, 48 and 72 hours showed the affected epithelial cells to have nonspecific changes in tubule ultrastructure, i.e. dissociation and segregation of tubule components as well as degranulation, fragmentation and hypertrophy. The dissociation of nucleolus components is followed by the damage of an essential part of cell mitochondrial apparatus and becomes irreversible. In some damaged cells degranulation is accompanied by the nucleolus decay into separate solid fragments formed of fibrous tissue. The enlargement of nucleolus fragments in the absence of proribosomes speaks in favour of the depression of proribosome formation process while the ability to synthesize p-RNA in comparatively slight.     

Norepinephrine-induced cardiac hypertrophy and fibrosis are not due to mast cell degranulation

The norepinephrine (NE)-induced hypertrophy of the left ventricle (LV) in the rat is preceded by increased interleukin (IL)-6 expression and associated with LV fibrosis. We have examined whether the elevated level of IL-6 may be due to mast cell degranulation. Therefore we tested the effect of cromoglycate sodium salt (cromolyn), an inhibitor of mast cell degranulation with anti-inflammatory and membrane-stabilizing activity, on the increased expression of IL-6 mRNA and of mRNAs of proteins involved in the remodelling of the extracellular matrix (ECM) which is induced by NE (0.1 mg/kg·h). After 4 h, the NE-induced increase in IL-6 mRNA expression was not influenced by cromolyn (20 mg/kg·h). Cromolyn-infusion for 3 days did not affect the extent of LV hypertrophy induced by NE, as measured by the LV weight/body weight (LVW/BW) ratio and by atrial natriuretic peptide (ANP) expression. Cromolyn induced a slight depression of the NE-induced elevation of the matrix metalloproteinase (MMP)-2. However, it did not affect the NE-induced elevated levels of mRNAs of collagen I and III and the tissue inhibitor of matrix metalloproteinase (TIMP)-2. Since cromolyn did not reduce the NE-effects in rat hearts in vivo we conclude that mast cell degranulation seems not to be involved in them.     

Microtubules in thyroidectomy cells of the rat anterior pituitary gland.

Microtubules were successfully illustrated in thyrotrophs and thyroidectomy cells of rat pituitary glands. In contrast, microfilaments were mostly seen in the nonglandular follicular cells. Numerous microtubules were observed in the early stages of development of the thyroidectomy cells. In thyroidectomy cells microtubules were located in close proximity to mitochondria, endoplasmic reticula, secretory granules, and membranes of Golgi complexes. Consequently, it is suggested that microtubules may play a role in degranulation or other processes associated with the hypersecretory state.     

Role of the pituitary-adrenal system in mechanism regulating vascular permeability during stress

Disturbances of the microvascular permeability were studied by the "vascular labelling" technique during the immobilization stress of hypophysectomized and adrenalectomized rats. Animals with sham operations served as controls. As revealed, hypophysectomy and adrenalectomy caused disturbances of vascular permeability in the mesentery. Vascular permeability disturbances in the hypophysectomized and adrenalectomized rats under conditions of immobilization were more expressed than in the sham-operated animals. Removal of the pituitary and adrenal glands produced mast cell degranulation at the earlier immobilization period.     

The effects of aromatizable androgens,non-aromatizable androgens,and estrogens on gonadotropin release in castrated African catfish,Clarias gariepinus (Burchell)

Summary To study the feedback mechanism of gonadal hormones on GTH secretion in male African catfish, the effects of castration and steroid replacement on GTH release, pituitary GTH content, and ultrastructural appearance of gonadotropes were investigated.Castration resulted in an increase in plasma GTH levels, a decrease in pituitary GTH content, and a degranulation of many gonadotropes. The aromatizable androgens testosterone and androstenedione were able to abolish the castration-induced increase in plasma GTH. This was accompanied with a restoration of pituitary GTH content and a regranulation of gonadotropes. The non-aromatizable androgens 5-dihydrotestosterone and 11-hydroxyandros tenedione did not have these effects. Replacement with estrone or estradiol resulted in an increase in pituitary GTH, however, without abolishing the elevated plasma GTH levels; ultrastructurally, many gonadotropes showed a welldeveloped granular endoplasmic reticulum together with a regranulation.The results of the present study indicate the significance of androgen aromatization in the feedback mechanism of gonadal steroids on the brain-pituitary axis.     

Fluorescamine as a histochemical reagent: Demonstration of polypeptide hormone-secreting cells

Summary Fluorescamine is a useful fluorescence microscopic reagent for the demonstration of certain peptide hormone-secreting cells in formaldehyde-fixed tissues. Among the cells demonstrated are the pituitary GH cells. the gastrin cells, the insulin cells and the thyroid C cells. In the latter cell system degranulation brings about a marked decrease in the intensity of the fluorescamine-induced fluorescence suggesting that the fluorogenic component is associated with the secretory granules. In models neither of the hormones tested—GH, gastrin, insulin—gave fluorescamine-induced fluorescence after pretreatment with formaldehyde. It is suggested that the fluorescamine-induced fluorescence of the endocrine cells demonstrates granular components distinct from the hormones.