Graafian follicle. Light micrograph of a section through a Graafian follicle containing a nearly mature egg, in the cortex of a healthy ovary. At lower centre is the rounded full-grown secondary oocyte (egg). It must undergo meiotic division before it can be fertilised. The egg is surrounded by pink cells forming a Icorona radiata (CR). i The ICR i is made of Izona granulosa i cells that stretch around the periphery of the follicle. A large grey Ifollicular antrum i is fluid-filled. At ovulation, the Graafian follicle ruptures and the mature egg (ovum) surrounded by ICR i leaves the ovary to pass into a fallopian tube for fertilisation. Stained with Azan. Magnification: x18 at 35mm size.