Observations on the granulosa cells of Acanthobrama terrae-sanctae and Tilapia nilotica (Teleostei)

PAS-positive yolk particles occur in the granulosa cells and in the chorional canaliculi of Acanthobrama which together with demonstrable alkaline phosphatase activity in the granulosa, suggests that the cells of this layer are involved in the transport of yolk proteins to the developing oocyte. Formation of the micropylar aperture in the chorion of Acanthobrama oocytes is attributed to phagocytic activity of specialized granulosa cells at the animal pole of the oocyte. The lack of histochemically demonstrable hydroxysteroid-dehydrogenase activity in Acanthobrama and, in Tilapia, the presence of acid phosphatase activity in atretic follicles, indicate that in these species atretic follicles do not have an endocrine function.