Autoradiography after tritiated thymidine labeling of the abortive gametogenesis in hybrid male ducks from the cross male Pekin X female Barbary]

This autoradiographic data concludes that meiotic prophase of the abortive gametogenesis of the sterile hybride drake (from the mating Peking male = Anas platyrhynchos L. X Barbary female = Cairina moschata L.) lasts 5 days 1/4. 6 days after the injection of the marker the seminiferous tubules contain numerous labeles necrosing cells but never typical elongated spermatids.     

Ultrastructural aspects of cells with 3 beta-HSDH (delta 5-3 betahydroxysteroid dehydrogenase) activity in female ducks. II. Female Barbary ducks (Cairina moschata)]

The cells making up the thin internal theca of the follicle of the Barbary duck and which contain are 3 beta HSDH enzyme show all of the ultrastructural characteristics of steroid cells: a well-developed smooth reticulum, tubular cristae mitochondria, a considerable load in lipid inclusionologous cells of the Peking duck since they are constantly more dense and their cristae are bigger and less numerous.     

The germinal population at embryonic stage and young age in the female hybrid duck born of male Pekin x female Barbary crossing. Comparison with ducks of the parent species]

As hatching the number of left ovary germinal cells of the female hybrid (Anas platyrhynchos x Cairina moschata) is weaker than that of the Peking and Barbary females because the small size of the genital crest limites the number of colonising germinal cells. As well after 16 days of incubation the multiplication of the oogonies stops in a way that we can not explain. The later growth of the ovarian follicle is, however, very fast, and the first laying is earlier than with the female parents.     

Ultrastructural aspects of cells with 3 beta-HSDH (delta-5-betahydroxysteroid dehydrogenase) activity in female ducks. I. Female Peking duck (Anas platyrhynchos)]

The cells making up the thick internal theca of the follicle of the Peking duck and which contain an active 3 beta HSDH enzyme have a developed smooth reticulum, tubular crested mitochondria, a considerable load in slightly osmiophilic lipid inclusions; all of these characteristics are those of steroid cells. Various physiological states of these cells juxtapose themselves in different proportions according to the season.     

Ultrastructure of 3 beta HSDH (delta 5-3 beta hydroxysteroid dehydrogenase)-containing cells in ducks. III. Hybrid ducks (Anas platyrhynchos male X Cairina moschata female) during egg laying]

All the cells of the ovary of the hybrid duck (Peking duck X Barbary duck) which contain an active 3 beta HSDH enzyme show ultrastructural characteristics of steroid cells: a smooth, developed reticulum, tubularcrested mitochondria, a considerable "charge" in lipid inclusion. These cells are found not only in the internal theca of follicles as with the female gender, but also in the cortical zones void of germinal elements, a tendancy particular to the female.     

Identification by immunofluorescence of various categories of anterior pituitary gland cells (somatotropin, prolactin, corticotropin, melanotropin, gonadotropin, and thyrotropin cells) in the spermophile (Citellus variegatus)]

Using antibodies against human STH, rat prolactin, 1-24, 17-39-synthetic ACTH, alpha- and beta-synthetic MSH, ovine LH, porcine LH beta, bovine TSH saturated with LH, it is possible to identify somatotropic, prolactin, corticotropic, melanotropic, gonadotropic and thyreotropic cells in the adenohypophysis of rodents Citellus variegatus and Graphiurus murinus. The topographical repartition and morphological characters of these cells are described.     

Presence of angiotensin II in the adult male rat anterior pituitary gland: immunocytochemical study after cryoultramicrotomy

Angiotensin II (AII)-like immunoreactivity and binding sites have recently been demonstrated at the pituitary level. This peptide also exerts a stimulatory effect on anterior pituitary hormone release. Immunocytochemistry on ultrathin sections obtained by cryoultramicrotomy was used with the aim of localizing endogenous AII-like material at the cellular and subcellular levels of the anterior pituitary gland. AII-like immunostaining was observed only in gonadotrophs, lactotrophs, and corticotrophs. In gonadotrophs, AII-like immunoreactivity was restricted only to secretion granules. In the two other immunoreactive cells, lactotrophs and corticotrophs, immunostaining was observed in the cytoplasm and in the nucleus. In the cytoplasm, AII-like material was visualized in the cytoplasmic matrix and in the secretory granules. In the nucleus, immunostaining was distributed in the euchromatin in the vicinity of the heterochromatin. AII-like immunoreactivity was also seen at the plasma membrane, but only scarcely. No reaction product was found when anti-AII serum preincubated with AII was used. These immunocytochemical results (1) provide evidence that gonadotrophs are only a site of synthesis and/or storage of AII-like material, (2) indicate that lactotrophs and corticotrophs are cells for AII and (3) provide cytological evidence for a direct participation of AII in the regulation of the lactotropic and corticotropic function.     

Differentiation of somatotropin and prolactin cells in the anterior pituitary gland of domestic cats under experimental conditions

The function of pituitary STH- and PRL-cells was studied under treatment of bromocriptine and haloperidol in 6-day old house cats. After histological staining, the intensity of the intracellular reaction was determined by a microphotometric technique. Additionally, the STH and PRL blood levels were measured by radioimmunoassays.     

Immunohistochemical and ultrastructural study of anterior pituitary cells in the female Afghan pika,Ochotona rufescens rufescens

An immunohistochemical study of the anterior pituitary gland of the female Afghan pika was carried out to distinguish the ultrastructural features of GH, PRL, ACTH, TSH and LH cells. The histochemically identified GH cells resembled ultrastructurally oval or round GH cells of the rat laden with large, dense secretory granules. PRL cells were divided into three subtypes based on differences in the diameter of their spherical secretory granules. They lacked polymorphic or irregularly shaped secretory granules. ACTH cells resembled ultrastructurally, in some respects, Siperstein's "corticotrophs" of the rat with peripheral arrangement of secretory granules. However, they were not always stellate, but elongate or angular in shape. The dense secretory granules were concentrated in the peripheral area of cytoplasm. TSH cells were non-stellate, but usually oval in shape, containing the smallest spherical secretory granules (100-200 nm in diameter). Almost all LH cells reacted also with FSH antiserum. They were irregular in shape, sometimes in contact with or surrounded the GH cells. They contained an abundance of medium-sized secretory granules (140-260 nm in diameter) which were larger than those in the LH cells of the female rat throughout the estrous cycle. Large secretory granules in the LH cells of the female pika seemed to be related to the endocrine state of persistent estrus.     

Olfaction in peking ducks (Anas platyrhynchos): A comparative study of centrifugal and centripetal olfactory connections in young ducks and in embryos and ducklings (Aves)

Summary Our study of young white Peking ducks (Anas platyrhynchos) revealed that their main olfactory centres are very similar to those reported for pigeons. Additionally, two major olfactory tracts and other olfactory centres were found to be intimately associated with telencephalic and diencephalic limbic structures. Our results make it possible to reject the view that olfaction in birds is not connected with the limbic system, as is the case in other vertebrates. The occurrence of olfaction was found to be considerably higher in embryos and ducklings. Embryonic connections are more extensive than the olfactory structures of young ducks, covering the archipallial wall of the hemisphere, i.e. the dorsomedial hippocampus and the main laminae of the forebrain. Transitory centripetal olfactory connections develop in embryos, and centrifugal olfactory connections are present in ducklings at the time of hatching. Controls revealed that a portion of the olfactory connections is drastically reduced by physiological degeneration involving connections emanating from both directions. Ultrastructural examination of embryonic archipallial structures revealed that the degeneration is partially the result of the dispersal of innervated neurons. Phylogenetically, one may compare the significant involvement of transitory olfactory connections in the anlage of limbic structures with the conditions occurring in anamniot vertebrates. This supports the hypothesis that the primary development of transitory olfactory connections represents an ontogenetic recapitulation of ancestral conditions, by which the structural and functional organization of the avian brain is influenced.     

Stimulation of anterior pituitary prostaglandin E content and somatotropin (growth hormone) synthesis by phospholipase A.

The prostaglandin E content of dispersed rat anterior pituitary glands was found to increase in the presence of phospholipase A or arachidonic acid. The increases were abolished by the addition of indomethacin. Similarly, the rate of somatotropin (growth hormone) synthesis was increased by these two agents, and the increases were again abolished by indomethacin. Phospholipase A also stimulated somatotropin release. The stimulation of prostaglandin E accumulation was a specific response to those fatty acids that are precursors for prostaglandin synthesis. One such precursor, [3H]arachidonic acid, was incorporated by rat anterior pituitary glands in vitro, and found to be associated mainly with phosphatidylethanolamine-like material. It is concluded that the intracellular concentration of prostaglandin E is limited by the availability of precursor fatty acids and that this can be increased by the addition of exogenous precursors or by the action of exogenous phospholipase A on the cellular phospholipid. Factors that increased prostaglandin E concentrations also increase the rate of synthesis of somatotropin, providing further evidence for the concept that prostaglandin E is involved in modulation of the rate of synthesis of this hormone.     

Adenosine regulates the release of adrenocorticotropic hormone (ACTH) from cultured anterior pituitary cells

We have recently shown the presence of adenosine receptors coupled to adenylate cyclase in anterior pituitary and in the present studies we have investigated the effects of adenosine on ACTH release. The R-site specific analogs of adenosine such as N-Ethylcarboxamide adenosine (NECA), L-N⁶-phenylisopropyl adenosine (PIA), 2-chloro-adenosine (2-Cl-Ado) all stimulated ACTH release in a dose-dependent manner. NECA was the most potent analog and stimulated ACTH release by about 170% with an apparent Ka of 0.1 µM, whereas PIA and 2-Cl-Ado were less potent and stimulated the release by about 110% and 125% with an apparent Ka of 0.2 and 0.4 µ-M respectively. The stimulation of ACTH release by NECA was inhibited by 3-isobutyl-1-methylxanthine (IBMX). On the other hand, adenosine deaminase (ADA) treatment of the cells also stimulated ACTH release as well as adenylate cyclase activity by about 2-fold, suggesting that endogenous adenosine plays an inhibitory role in the release of ACTH. Other agents, such as corticotropin-releasing factor (CRF), vasoactive intestinal peptide (VIP) and forskolin (FSK) also stimulated ACTH release from these cells. In addition, the stimulation by an optimal concentration of NECA was almost additive with maximal stimulation caused by VIP and FSK. These data suggest that adenosine modulates ACTH release from anterior pituitary through its interaction with adenosine receptors coupled to adenylate cyclase.Abbreviations NECA N-Ethylcarboxamideadenosine - PIA L-N⁶-Phenylisopropyladenosine - 2-Cl-Ado 2-chloroadenosine - FSK Forskolin - VIP Vasoactive Intestinal Peptide - CRF Corticotropin Releasing Factor - ADA Adenosine Deaminase - IBMX 3-Isobutyl-1-methylxanthine     

A correlative radioimmunoassay and immunohistochemical study of LHRH-induced LH depletion in the anterior pituitary of male and female neonatal rats in vitro

Summary After an exposure of 24 h to synthetic LHRH (100 ng/ml) in vitro, the anterior pituitaries of 4-day-old rats show a notable loss of immunoreactive material in most LH cells in males, but not in females. When radioimmunoassayed without incubation, the pituitary LH content of 4-day-old female rats is 2.8 times higher than that of males of the same age. LHRH treatment stimulates a higher rate of LH discharge in females than in males, but if LH release is expressed as a percentage of the initial pituitary LH content, there is no apparent difference. In both sexes, more than 70% of the initially stored LH is discharged into the medium after 24 h of LHRH stimulation. In males, this discharge produces a pronounced depletion, but in females, the pituitary still contains 78.2% of the initial LH content despite the large amount of hormone released.From these results, it is concluded that in newborn rats the LH synthetic rate in females is higher than that in males. This high synthetic activity, together with the large store of LH, may explain why prolonged LHRH treatment fails to cause LH depletion in females. At 4 days of age LHRH had no stimulatory effect on pituitary synthesis of LH in either sex.