Ultrastructural comparative investigations on the hypophysary cells in fresh-water teleosts under natural conditions. The glycoproteic thyreotrope cells.
The structural und ultrastructural characteristics of the glycoproteic hypophysary cells - considered as TSH producers - were studied with optical and electron microscopical means in 7 species of freshwater teleosts: Leuciscus cephalus L., Barbus meridionalis petényi H., Chondrostoma nasus L., Gobio gobio carpathicus Vlad., Phoxinus phoxinus L., Nemachylus barbatulus L. and Cobitis taenia L., during the reproductive period and in the period of sexual rest. These cells are present in a relatively reduced number in the hypophysis, forming islets of 2...3 cells, each. They are of small dimensions (the maximal diameter being 7 micron) having polyhedral form with prolongations or an ovoidal form. The cellular nucleus is of large dimensions (to 5 micron) often deformed or segmented. The cytoplasm, during the reproductive period, contains numerous moderately electrondense secretory granules. The mean diameter of the granules does not exceed 1200 A in any of the species studied. In the reproductive period the mitochondria are swollen and prolonged, the Golgi complex more developed and in some species a large number of microvesicles is spread around this complex. The researches proved the tight connection of these cells with the nerve fibres which contain or not neurosecretory peptidergic granules. The more intensive elaboration of the granules during the reproductive period is discussed.
D000818:Animals; D005260:Female; D005399:Fishes / Q000033:anatomy & histology*; D008297:Male; D010902:Pituitary Gland / Q000648:ultrastructure