D�tection par immunofluorescence des cellules corticotropes et m�lanotropes dans l'hypophyse de la grenouille, Rana temporaria L., au cours du d�velopp�ment

Immunohistochemical study on the development of the adenohypophysial cells in the lizard Gallotia galloti

Immunohistochemical methods have been used to study the embryonic and postnatal development of the hormone-producing cells in the adenohypophysis of the lizard Gallotia galloti. In this species, Rathke's pouch is formed between stages 30 to 32 of the embryonic development, although the first sign of immunoreactivity to antisera against adenohypophysial hormones occurs in stage 33 in the pars distalis anlage. These cells derive from the dorsal face of Rathke's pouch and are immunoreactive to anti-ACTH serum. The cytodifferentiation of ACTH and MSH cells occurs in the pars intermedia in stage 34. The TSH cells appear at stage 35 and the gonadotrope cells at stage 37. These cells derive from both the dorsal and ventral face of the Rathke's pouch. The LTH cells are revealed at stage 39 and are only originated from the dorsal face. The STH cells, which come from the dorsal as well as ventral face, are the last secretory cells differentiated just before hatching. During postnatal development an increase and also a redistribution of the immunoreactive cells occur until acquiring the adult distribution.

Cytodifferentiation and immunocharacteristics of adenohypophysial cells in the toad, Bufo melanostictus

Employing the unlabelled antibody enzyme technique cytodifferentiation, immunocharacteristics and topographical distribution of melanotropic (MSH), adrenocorticotropic (ACTH), thyrotropic (TSH), prolactin (PRL), gonadotropic (GTH) and growth hormone (GH) secreting cells in the embryonic/larval as well as adult pituitary gland of the common Indian toad, Bufo melanostictus, have been studied by using antisera raised in rabbit against mammalian hypophysial hormones. Immunoreactive MSH and ACTH cells appear first in the dorsocaudal and rostral regions of the pituitary anlage (PA) at stage 21 (Gosner's classification) of the embryonic development. This is followed by the differentiation of TSH and PRL cells at stage 22 in the midventral and central regions of the PA respectively. Finally, at stage 23 the GTH cells appear in the rostral and the GH cells in the caudal regions of the PA. With the progress of the development, cells showing immunoreactivity to various antisera gradually increase in number, size, granular content and finally occupy the characteristic adult disposition. The MSH cells comprise the pars intermedia. In the pars distalis (PD) the ACTH cells are localized in the rostroventral region, TSH cells in the central region and the GH cells in the dorsocaudal region. However, GTH and PRL cells are distributed throughout the PD.

[Immunofluorescent localization of pituitary hormones during embryonic development of Nectophrynoides occidentalis Angel]

From premetamorphosis (end of stage Ib) of Nectophrynoïdes occidentalis (viviparous anuran amphibian) MSH cells are revealed in the pars intermedia of pituitary using cytoimmunofluorescence technique. At the same stage, ACTH-STH-PRL and LH cells are revealed in the pars distalis. The comparison of the order of appearance of different cell categories in the adenohypophysis (considered in the functional point of view) among the embryos of Nectophrynoïdes and the tadpoles of different amphibians allows the emphasis of some analogies and divergences.

Immunohistochemical demonstration of TSH-, LH- and ACTH-cells in the hypophysis of tadpoles of Xenopus laevis D

By use of the immunofluorescence technique TSH-, LH- and ACTH-cells were localized in the hypophysis of tadpoles of Xenopus laevis. The first signs of the activity of these cells were observed in early stages of the development, i.e., stage 39 for ACTH, and stage 42 for TSH and LH.

Immunocytological study on the differentiation of chick and quail adenohypophysis epithelial rudiments, grafted or cultivated in vitro: evidence for polypeptidic hormones

Epithelial rudiments of adenohypohysis were removed from chick and quail embryos between days 3 and 5 of development. Chick rudiments were grafted for 11--13 days onto the chorioallantoic membrane of decapitated chick embryo hosts. Quail rudiments were cultivated in vitro for 6 days. Both grafted and cultivated Rathke's pouches differentiated into adenohypophyseal tissue. The adenohypophyseal tissue cultured on chorio-allantoic membrane exhibited cells reacting with the following immune sera: anti-beta-(1--24)ACTH, anti-alpha-(17--39)-ACTH, anti-alpha-endorphin, anti-beta-endorphin and anti-beta-LPH, which also gave a positive reaction when applied to adenohypophysis of corresponding age which had differentiated in situ. In situ, corticotrophs were located exclusively in the cephalic lobe of adenohypophysis. Therefore, the differentiation of corticotrophs in the whole graft, i.e., from both cephalic and caudal lobes of Rathke's pouch, showed that the cells of the caudal lobe, or at least some of them, were uncommitted when the rudiment was removed. In vitro, tissue derived from Rathke's pouch contained cells reacting with antibodies to beta-(1--24)-ACTH, alpha-(17--39)-ACTH, and beta-LPH, as did adenohypophysis from quail embryos of corresponding age (9--10 days), differentiated in situ. The differentiation of quail Rathke's pouch in vitro corroborates that differentiation can occur without influence from hypothalamus and, moreover, shows that at least some kinds of cells can differentiate without influence exerted by any other encephalic factors, and in the absence of mesenchyme. The question arises whether fibroblastic cells derived from Rathke's pouch cells act as feeder-cells and/or secrete some factors promoting differentiation.