The sperm hook in house mice: a functional adaptation for migration and self-organised behaviour

Abstract

Mouse sperm has a falciform apical hook at the head of the sperm. In this study, we investigated the function of the sperm hook while migrating through the female reproductive tract inMus musculus(C57BL/6), using custom-built two-photon microscopy. Our observations indicate that sperm hook plays a probe-like role to facilitate sperm interaction with the epithelium during migration and an anchor-like role to secure onto the epithelia of the uterine and oviduct. We found no direct evidence of sperm trains being beneficial in their migration. While the sperm hook may be a key for sperm cooperative behaviour in other rodent species, our results suggest that in house mice, the sperm hook plays a role in sperm migration through female reproductive tract, but not for cooperative behaviour, except for synchronised sperm beating.