A photomicrograph of a stained semi-thin section of mouse ovary, showing a maturing Graafian follicle. The ovary contains many follicles that contain immature oocytes (egg cells). The follicle is important to support maturation and also develops through a number of stages as the ooctye matures. This process of folliculogenesis includes; the immature dormant primordial follicle, primary follicle, secondary follicle and tertiary stage follicle before ovulation occurs. The tertiary stage follicle is also called an antral or Graafian follicle characterised by a large fluid filled space (or antrum). The Graafian follicle also contains a fully mature oocyte at its full size complete with zona pellucida. Scale = 1.1mm