Ovarian Folliculogenesis in Mammals: A Qualitative and Quantitative Analysis

Abstract

Female fertility depends on the supply and maturation of the ovarian germ cells, i.e., the oocytes, and the differentiation and proliferation of granulosa and theca cells. During prenatal life, the ovarian cortex increases as the ovigerous cords become more extensive, convoluted and elongated and contained germ cells and pregranulosa cells. The formation of primordial follicles first occurred at the cortico-medullary junction and migrated towards the periphery of cortex, however the other follicles appear at late gestation. Recent classification of follicular atresia as antral and basal type is equivalent to first and second degree of obliterative atresia, respectively. This review reports current knowledge and proposes novel hypotheses that can formulate the contribution of germ cells to ovarian differentiation and folliculogenesis.