Oogenesis begins with the primordial germ cell, which divides mitotically from 5 weeks of embryonic life and is called the oogenic cell. From March to July of the embryo, oogenic cells successively enter the first meiotic division and abort at prophase bilineage, renamed the primary oocyte, which forms the primordial follicle with the surrounding granulosa cells. The bilinear stage is characterized by the formation of germinal follicles. The germinal follicles persist until they disappear before ovulation. The lifelong oocyte reserve is completed during the fetal period, peaking at approximately 7 million at about 20 weeks. At birth, there are about 2 million left, and at menarche about 300,000-400,000 oocytes develop into mature eggs, but only 400-500 of them eventually develop into mature eggs during a woman’s lifetime. 99.9% of all oocytes are atretic, and by the time of menopause the oocytes are largely depleted. The primary follicles develop into primary follicles, secondary follicles, and mature follicles by the action of FSH. The follicles are about 50 μm in diameter, the primary follicles are about 100 μm in diameter, and the mature follicles can be 100-130 μm in diameter. 85 days are required for the growth of a follicle to reach its final maturity. Before ovulation, the egg completes the first meiotic division and expels the first polar body to become a secondary oocyte, which stays in the middle of the second meiotic division waiting for fertilization. After fertilization, the oocyte resumes meiosis and expels the second polar body, followed by the formation of the male and female protoplasts.