Luteinization in the atresia of maturing ovarian follicles in mouse.

Maturing ovarian follicles undergoing atresia were ultrastructurally analyzed. Using the method of Okrös (1968) the process of luteinization was traced, taking place in the basal layer of cells of granulous membrane and in the cells of inner layer of theca interna during the atresia. In the atresia process, numerous electron dense granules arranged in packets and surrounded by tubular mitochondria are observed in the basal cell layer of granulous membrane. A considerable accumulation of the grains of reaction product and the presence of tubular mitochondria are also found in the cells of theca interna. Such a behaviour of those cells can be associated with an enhanced production of steroid hormones (mainly estrogens) in atretic follicles.