The follicles develop to about 1.8-2.5 cm in diameter and then rupture and expel. There is also a case where the follicles develop to a normal size but do not rupture and expel to form a flavinized cyst. The follicle is the largest body cell in the body and is also a germ cell. The most primitive follicle already exists in the ovary from the embryonic period. Before puberty the follicles are in an atretic state. After sexual development, follicles begin to develop after the end of each menstrual period and experience about 7-12 days to mature and ovulate. The egg can survive for about 2 days after ovulation. If the egg meets sperm it will form a fertilized egg and develop into a fetus, otherwise the egg will die and be expelled from the body.