Overview Oogenesis Oogenesis development of mature oocytes, or haploid gametes capable of fertilization by sperm Oogenesis Pre-natal oogenesis oogenesis, or maturation of oocytes, begins in fetal life primordial germ cells migrate from fetal hind gut to gonadal ridge login to view 1 more bullet in fetal ovary, oogonia proliferate by mitotic divisions login to view 1 more bullet oogonia (2N, diploid) differentiate to primary oocytes (2N, diploid) login to view 3 more bullets Post-natal oogenesis oogenesis, or maturation of oocytes, continues in post-puberty adult life in follicular (proliferative) phase of menstrual cycle, development of primordial follicles yields one dominant, pre-ovulatory Graafian follicle primary oocyte (2N, diploid) differentiates to secondary oocyte (2N, haploid) login to view 2 more bullets at ovulation, Graafian follicle ruptures and releases secondary oocyte login to view 2 more bullets