Fig. 2. Connexin localization in the cumulus-oocyte complex (COC) as detected by confocal immunofluorescence microscopy. In single-labelling experiments, Cx37 (anti-Cx37, red) was localized to gap-junction plaques (arrow) on the surface of the oocyte (O), beneath the zona pellucida (ZP) in both cultured COCs (A) and follicle sections (B). In other single-labelling studies, Cx43 (anti-Cx43, green) was localized to plaques (arrow) between contacting granulosa cells (GC) in follicle sections (C). In double-labelling experiments, no Cx37 immunostaining was detected when Cx37-deficient COCs were immunolabelled (D, note lack of red signal) or when the anti-Cx37 antiserum was competed with the immunizing peptide in cultured COCs (E, note lack of red signal). Cx43 was localized to plaques between granulosa cells in D and E. Bars=10 µm.