The ovary is much smaller during fetal life than in adulthood (30 times lighter at birth than at puberty). Yet, the number of germ cells is several times higher before birth than during the reproductive years (6–7 million at 20 weeks gestation, 0.5–1 million at birth, 300,000 at puberty, and less than 1000 at the end of menopause [1]). Thus, it is not surprising that the gross and microscopic features of the ovary continue to change throughout life, reflecting the steady decline of germ cells and the differences in folliculogenesis during fetal development, childhood, and after puberty. This chapter focuses on the histological features of the fetal ovary and highlights the differences from the adult ovary.