At What Size Does The Follicle Rupture?

Follicles mature and rupture at 18 to 20 mm size. Ovulation happen around 12^th to 18^th day of Cycle. Follicles are minute in size at the beginning of menstrual cycle. Gradually the follicles increase in size under hormone effect. As a result the follicles grow to the size of 20 mm. At this size chemical stimulation helps rupture and release of egg. Consequently the egg is picked up by the fallopian tube for fertilisation.