Adrenocortical and adrenomedullary homologs in eight species of adult and developing teleosts: morphology, histology, and immunohistochemistry.

Morphology, histology, and immunohistochemistry of the adrenocortical and adrenomedullary homologs (adrenal glands) of the following developing and adult teleosts were examined: Salmoniformes-Oncorhynchus mykiss (rainbow trout), Salmo trutta fario (brown trout), Coregonus lavaretus (white fish); Cyprinodontiformes-Gambusia affinis (mosquito fish). Perciformes-Dicentrarchus labrax (sea bass), Sparus aurata (sea bream), Diplodus sargus (white bream), Oblada melanura (saddled bream). The anatomical relationships of the gland with the renal system and venous vessels were also noted. In adults of all species steroidogenic and catecholaminergic chromaffin cells were found in the head kidney, which is pronephric in origin and subsequently transformed into a hematopoietic lymphatic organ. In Perciformes, chromaffin cells are distributed around the anterior and posterior cardinal veins and ducts of Cuvier; in Salmoniformes, around the posterior cardinal veins and in the hematopoietic tissue; and in G. affinis, around the ducts of Cuvier and posterior cardinal veins, while a few are visible also around the sinus venosus. In Perciformes and Salmoniformes, numerous chromaffin cells are also present in the posterior kidney, derived from the opisthonephros, in contact with the caudal vein. Steroidogenic cells are always confined to the head kidney. During development chromaffin and steroidogenic cells appear early after hatching in the pronephric kidney, at the level of the ducts of Cuvier and of the cephalic part of the posterior cardinal veins. Later, chromaffin cells in Perciformes reach the anterior cardinal veins, and subsequently, in both Perciformes and Salmoniformes, they reach the developing posterior kidney. Their localization along the posterior kidney is still in progress about 4 months after hatching and is completed about a year after hatching. These findings support the concept that the structure of the adrenal gland in teleosts is intermediate between that of the other actinopterygians and that of tetrapods. The development differs from that of tetrapods in that it occurs mainly in the pronephros and only later do chromaffin cells reach the opisthonephric kidney.

Active cell movements and embryonic cholinesterase in the postmetamorphic completion of the adrenal morphogenesis in frogs.

The adrenal gland in Rana esculenta complex, as in other advanced anurans, is not yet in its definitive position at the end of the metamorphosis and reaches it subsequently, before sexual maturity. The displacement takes place by various means, among which active cellular movements prevail. These are demonstrated by the presence of acetylcholinesterase (AChE) in noninnervated cells (embryonic AChE). The disintegration of the connective tissues which delimit the cords of the adrenal gland, the passive transport of cells by the blood vessels and the movements of adjacent renal and mesenchymal cells collaborate with the active movements of the adrenal cells.

The adrenal gland of Euproctus (Urodela, Salamandridae): comparison of three species and phylogenetic inferences.

Adrenal glands of three species of Euproctus (E. asper, E. montanus and E. platycephalus) were compared. Differences were observed as regards: (1) the distribution of the adrenal tissue, which is more sparse in E. asper than in the other two species; (2) the amount and size of the adrenal islets: in E. asper, they are numerous and small, in E. platycephalus, they are decreased in number and larger, in E. montanus they are few and very large; (3) the distance of the islets from the medial border of the kidney is variable in E. asper; in E. montanus they are mostly in contact with the medial edge, whereas in E. platycephalus they are distant from it. The adrenals of E. montanus and E. platycephalus are more similar to each other than to that of E. asper; the gland in this species may be considered a more primitive type. Such structural relationships are in agreement with phylogenetic inferences concerning the three species.

Effects of follicle-stimulating hormone, luteinizing hormone and prolactin on left and right gonads of female chick embryos in culture.

Organotypic cultures were made of right female gonads of chick embryos of 8 days, on medium containing follicle-stimulating hormone, luteinizing hormone or prolactin (PRL), and of left ovaries of the same age on the medium containing PRL. Results indicate that the explants cultured on PRL resemble most closely the normal ovaries in vivo. It is suggested that PRL may have a function in the morphogenesis of the female gonads of chick embryos.