Apoptosis in different stages of human oogenesis.

Apoptosis is an active form of cell death characterized by a series of morphological changes that become particularly evident at the ultrastructural level. The majority of ovarian germ cells undergo degeneration during prenatal and reproductive life and only in recent studies has it been demonstred that this drop is due to an apoptotic process. We evaluated this process during human oogenesis in prenatal life and we studied the ultrastructural changes that occur in apoptosis in various phases of the meiotic process. From our observations it is clear that apoptosis involves two main phases of the meiotic process: an earlier one concerning the oogonia and oocytes in the preleptotene stage, and a later one that mainly concerns the oocytes in the pachytene stage.