The structure of the adenohypophysis of Aequidens pulcher (Teleostei, Cichlidae). I. Histological and immunohistochemical studies.
With standard staining techniques, five cell types can be identified in the pars distalis of the adenohypophysis of Aequidens pulcher; a sixth cell type prevails in the pars intermedia. Each of these cell types has been characterized immunohistochemically. Various treatments--metyrapone, thiourea, and thyroxine--have been used to confirm the identity of the corticotrophs and the thyrotrophs. It is concluded that the cells producing prolactin and growth hormone are tinctorially, immunologically, and topographically similar to descriptions for other teleosts. This also applies for the corticotrophs of the rostral pars distalis and the melanotrophs in the pars intermedia. The corticotrophs are stimulated by metyrapone treatment, on the basis of cell size and tinctorial properties, but immunohistochemical staining is not affected; thiourea, on the other hand, affects immunohistochemical, but not tinctorial, staining of the corticotrophs. The thyrotrophs are small, irregularly shaped cells in the rostrodorsal proximal pars distalis, adjacent to the neurohypophysis. They cross-react with an antiserum against bovine beta-TSH but (unlike the gonadotrophs) not with one against ovine LH. Thiourea treatment induces their hypertrophy, with a decrease in tinctorial and immunohistochemical stainability. Metyrapone, like thiourea, induces enlarged nuclei with pronounced nucleoli but, like thyroxine, also increases tinctorial and immunohistochemical staining. The gonadotrophs are basophilic, like the thyrotrophs, but cross-react with antisera against both bovine beta-TSH and ovine LH. These cells are not affected by any of the treatments used here. In some specimens, a second type of gonadotroph has been identified, which stains mainly with periodic acid-Schiff. The two types of gonadotrophs are immunohistochemically comparable.
D000818:Animals; D000936:Antigen-Antibody Complex / Q000032:analysis; D005399:Fishes / Q000502:physiology*; D007106:Immune Sera; D010903:Pituitary Gland, Anterior / Q000166:cytology*; D010908:Pituitary Hormones, Anterior / Q000032:analysis*; D013045:Species Specificity
D000936:Antigen-Antibody Complex; D007106:Immune Sera; D010908:Pituitary Hormones, Anterior