Microinjection of anti-Rab3A inhibits cortical granule exocytosis. A) Cortical granules of MII eggs microinjected with increasing concentrations of anti- Rab3A antibody (anti-Rab3A) or preimmune serum (IgG) prior to the activation of cortical granule exocytosis with SrCl2. After removing zona pellucida, cells were fixed, and mounted for cortical granules’ quantification. Shown are representative images for each condition in B. Scale bar, 50 μM. B) Quantification of the cortical granules’ density (% CG/100 μm2) in MII eggs microinjected with increasing anti-Rab3A concentrations or with IgG and activated with SrCl2. Data represent the means ± SEM of at least three independent experiments. The asterisks indicate significant differences from control condition (*, p<0.05; ***, p<0.001).