Fig. 3. Double-immunofluorescent labelling of cultured COCs revealed that Cx37 is localized to gap-junction plaques at the oocyte surface whereas Cx43 is localized to plaques between adjacent granulosa cells. Arrows indicate punctate localization of Cx37 (anti-Cx37, red) at the border between the oocyte (O) and granulosa cells (GC). Populations of intracellular Cx37 are visible within the oocyte and at candidate gap-junction plaques between adjacent GC. Cx43 (anti-Cx43, green) is localized to plaques between granulosa cells and is rarely found at the oocyte surface. Bar=10 µm.