Follicles appear during the fourth or fifth month of foetal development, and the number of follicles that are formed at this age constitutes the lifelong store of follicles for the individual throughout life. Post-mortem or ultrasonographic studies demonstrate small antral follicles in the prepubertal ovary, but prior to menarche all follicles that develop antra ultimately undergo atresia. The ovaries in the prepubertal child have a volume of 0.7-0.9ml, but following the onset of puberty the volume increases to 2-10ml. In the prepubertal state the uterus is tubular and 2-3cm in length, but during puberty it becomes bulbous and 5-8cm in length.
