Scanning electron micrograph (SEM) of ovarian follicle in rat. Even though this micrograph is of a rat follicle, this is exactly how any mammalian follicle, including human, would look. Follicle is the seat of oocyte development until ovulation. The fluid-filled cavity (antrum-seen as dark area) is surrounded by the granulosa cells. As the follicle ruptures at the time of ovulation, the oocyte is released and transported into the oviduct where it will be fertilized by the sperm. Magnification: 90x @ 35mm (525x at 8" x 10" print size).