Figure 3
Three-dimensional projections of mouse follicular oocytes collected at different times after the hCG injection. All oocytes were zona free and triple labeled with ABL2, LCA, and SyTox to see the DNA. Each oocyte sample was optically sectioned, and all optical sections of each oocyte were used to compile 3D projections which were animated. (A) Stage 1: oocyte in metaphase I shortly after germinal vesicle break down. (B) Stage 2: metaphase I oocyte showing the first cortical granule free domain over the spindle. (C–E) Stage 3: metaphase I to metaphase II transition showing a subset of LCA-binding cortical granules concentrated in a band around the cleavage furrow. C is a three-dimensional reconstruction while D and E show the LCA and ABL2 labels separately. (F–G) Stage 4: Later stage of polar body extrusion. LCA-binding cortical granules in the cleavage furrow have undergone pre-fertilization release. (G) Stage 4: Metaphase II oocyte with the first polar body extruded. LCA-binding cortical granule material has been released into the perivitelline space during pre-fertilization exocytosis (arrows). (H, I) Stages 5 and 6: oocytes in metaphase II showing the formation of the second cortical granule free domain.