Cortical F-actin, not cytoplasmic, positions the sperm. (A and B) Mid-focal plane (A) and cortical (B) views of F-actin. Bars, 10 µm. Lat A, latrunculin A. (C–F) Single–time-point images showing various cytoplasmic and cortical F-actin structures around the sperm (arrowheads). Bar, 5 µm. (G) Single frames of subcortical yolk granules in control and rab-7(RNAi) meiotic embryos. Bars, 10 µm. (H) Plot of yolk granule velocity against diameter from a cluster of 15 yolk granules in a rab-7(RNAi) meiotic embryo. (I) Scatter plot showing the Pearson r values from 11 yolk clusters in rab-7(RNAi). (J) Representative kymograph from time-lapse imaging at 5-s intervals. (K) Images from a time-lapse sequence where the sperm organelles maintain contact with the cortical actin. Bar, 5 µm.