| structure of the zona pellucida and cumulus oophorus in three species of native australian rodents. | the sperm head of many australian hydromyine rodents has three curved hooks projecting from its anterior margin; the structure of the hooks has been characterized, but their function is unknown. in this study, we have investigated whether the hooks might have evolved to assist sperm penetration through more formidable egg vestments, particularly the zona pellucida. cumulus-oocyte complexes were obtained from two species that possess a three-hooked sperm head (pseudomys australis and p. nanus) an ... | 1989 | 2777167 |