Contribution to the study o f topography and histology o f the glands: Stannius corpuscles and thyroid o f the pacu, Colossoma mitrei, Berg, 1895 (Cypriniformes, Characidae)

Abstract

This paper is concerned with the histological study of the Stannius corpuscles and thyroid gland of Colossoma mitrei, maturing males. The Stannius corpuscles are scattered laterally in the mesonephros. The glandular parenchyma consists of several incompletely delimited lobes with cells showing volumous nucleus and acidophilic cytoplasm, with coarse granulations, PAS weakly positive. In the thyroid follicles of pharingeal region the epithelium is flat cubic, whereas the follicles in the pronefric are lined by a single layer of epithelium likeness an endothelium. The lumen of the follicles is filled with acidophilic colloid. The colloid presents small number of vacuoles in it.