title: Cytophysiology and innervation of gonadotropic cells in the pituitary of the black molly (Poecilia latipinna). An electron microscopical study.
abstract: In the male black molly, poecilia latipinna, morphological and functional aspects of the gonadotropic (GTH-)cells have been studied at the ultrastructural level. The cells exclusively occupy the ventral and lateral areas of the meso-adenohypophysis. In the black molly there is evidence of the presence of only one type of gonadotropic cell. In the GTH-cells of most specimens, the rough endoplasmic reticulum is weakly developed. The secretory vesicles are characterized by cores with varying diameters; this variation was not observed in the secretory vesicles of the other types of pituitary cells, except in the TSH-cells. After applying a histochemical method for the demonstration of polysaccharides, small black deposits appear in the core of the secretory vesicles of the GTH- and TSH-cells only; this indicates the glycoproteinaceous nature of the hormones produced in these cells. Male black mollies treated with methyl-testosterone have significantly smaller GTH-cells and a lesser number of secretory vesicles and mitochondria in these cells. GTH-cell activity in Poeciliinae may be thus influenced by androgens by means of a negative feed-back mechanism. The GTH-cells are innervated by both type A and type B neurosecretory fibres. There are indications that the type A fibres may originate from the pars lateralis cells of the nucleus lateralis tuberis; the origin of the type B fibres is uncertain.
mesh_terms: D000818:Animals; D005399:Fishes / Q000033:anatomy & histology*; D006023:Glycoproteins / Q000032:analysis; D006065:Gonadotropins, Pituitary / Q000032:analysis*; D006651:Histocytochemistry; D007030:Hypothalamo-Hypophyseal System / Q000648:ultrastructure; D008297:Male; D008777:Methyltestosterone / Q000494:pharmacology; D008854:Microscopy, Electron; D010902:Pituitary Gland / Q000648:ultrastructure*; D010903:Pituitary Gland, Anterior / Q000648:ultrastructure*
chemical_list: D006023:Glycoproteins; D006065:Gonadotropins, Pituitary; D008777:Methyltestosterone