Figure 1

A transmission electron micrograph (×12,000) of a prophase-arrested, untreated ovarian follicle from hibernating Rana pipiens. An area of the oocyte cortex with vitelline membrane (VM), oocyte surface microvilli, cortical granules (CG) and yolk platelets (Y) was selected. Annulate lamellae (membrane array below center of figure), numerous mitochondria and other vesicles are visible. Follicles were fixed sequentially with OsO₄ and glutaraldehyde and post-fixed in 1% buffered OsO₄ for 1.5 h as described [18]. Samples were embedded in Epon and 50 to 80 nm sections were stained with uranyl acetate and then counter stained with lead citrate. Micrographs were taken using a Jeol 100 CX electron microscope at 80 KV.