Fine structure of the testicular gland of the black goby, Gibius jozo L.

Abstract

The homologue of mammalian Leydig cells in the testis of fish of the genus Gobius is believed to be a glandular mass lying along the mesorchium and quite distinct from the seminiferous region. This gland was studied in Gobius jozo by light and electron microscopy. Histologically, the gland is composed of cords of polyhedral cells located between the main vessels of the testis and the deferent duct. Dark and light cell varieties were observed both after staining with toluidine blue and with respect to their cytoplasmic electron density. The fine structure of the glandular cells is characterized by a well developed agranular endoplasmic reticulum in the form of random anastomosing tubules and vesicles and by very numerous mitochondria with tubulo-vesicular cristae. In some mitochondria the internal organization is paracrystalline. One or two bodies of unknown nature are Found in the Golgi region. They are partially limited by an unusually thick membrane and contain a material subdivided mostly into small vesicles. Liposomes and lipofuscin pigment granules are also present. The ultrastructural features of the glandular cells of the testis of Gobius jozo confirm a specialization in steroid hormone production.