Light micrograph of a mature, human ovarian (graafian) follicle (containing a secondary oocyte Potential ova arise within the ovaries, developing as primary follicles many of which do not reach maturity. Those which do not degenerate enlarge, leaving the oocyte surrounded by layers of cells (corona radiata) which forms a bridge with the follicular wall. This bridge breaks down before ovulation, when the follicle ruptures and releases the ovum into the peritoneal cavity, where it is received into the fallopian tube for potential fertilisation. Magnification: X 20 at 35mm size.