The structural organisation of sperm head components of the wombat and koala (suborder: Vombatiformes): an enigma amongst marsupials
WILLIAM G. BREED, CHRISTOPHER M. LEIGH AND MARIO RICCI
Department of Anatomical Sciences, University of Adelaide, Australia
The sperm head structural organisation of the koala and hairy-nosed wombat, and the eﬀects of varying concentrations of the ionic detergent, Triton X-100, on its component parts, were determined by electron microscopy. Although alike in form between the 2 species, the sperm nucleus of the former, but not the latter, had nuclear vacuoles and appeared to be more easily dispersed by the Triton X-100. The structure of the acrosome of the spermatozoon was similar between the 2 species and, in both, previously undescribed thin posterior and lateral segments were found to be present. It is suggested that this thin segment may facilitate sperm-zona and}or sperm-oolemma binding and fusion.