Fig. 2. TEM of cortical granules. (A) A mature C. elegans oocyte contains cortical granules (arrows); inset shows higher magnification of vesicles near the oocyte chromosomes (asterisks). (B) An embryo within the spermatheca contains a cortical granule near the plasma membrane (upper right arrow), and a cluster of heterogeneous vesicles (lower arrows). (C) A metaphase I embryo contains cortical granules (arrows) distributed across the cortex (asterisk denotes chromosome in spindle). The cortical granules are found in close association with reticulate ER (A-C). (D) Embryo at metaphase II (chromosome in spindle indicated by white asterisk) lacks cortical granules, and the polar body (black asterisk) is trapped between eggshell layers (arrows). Scale bar: 2 µm.