title: Spermatozoa of the old endemic rodents of Australia - the possible functional significance of their ventral processes.
abstract: Spermatozoa of the plains mouse (Pseudomys australis), like those of most Australian old endemic rodents, contain, in addition to an apical hook, two further processes that extend from the upper concave surface of the head, the ventral processes. This study shows that these processes contain thiol-rich cytoskeletal proteins, which presumably help to maintain their rigidity during sperm transport, together with the overlying cell membrane having abundant intramembranous proteins. To determine the possible functional significance of these processes, an in vitro study of spermatozoon-zona binding was undertaken. The findings suggest that initial sperm binding occurs by way of the cell membrane over the acrosome of the apical hook and that, subsequently, the lateral surfaces of the ventral processes also become tightly bound to the zona matrix. These ventral processes may therefore have evolved to increase sperm adhesion to the outer zona surface and/or to enhance stabilisation of the spermatozoon at the time of zona binding and initial penetration of the egg coat.
authors.affiliation: Discipline of Anatomy and Pathology, School of Medical Sciences, Faculty of Heath Sciences, The University of Adelaide, SA 5005, Australia.
authors.forename: Simon
authors.initials: S
authors.lastname: Drew
authors.affiliation: Discipline of Anatomy and Pathology, School of Medical Sciences, Faculty of Heath Sciences, The University of Adelaide, SA 5005, Australia.
authors.forename: Chris
authors.initials: C
authors.lastname: Leigh
authors.affiliation: Discipline of Anatomy and Pathology, School of Medical Sciences, Faculty of Heath Sciences, The University of Adelaide, SA 5005, Australia.
authors.forename: William G
authors.initials: WG
authors.lastname: Breed
mesh_terms: D000818:Animals; D001315:Australia; D021961:Cell Membrane Structures / Q000378:metabolism / Q000502:physiology* / Q000648:ultrastructure; D003598:Cytoskeletal Proteins / Q000378:metabolism; D005260:Female; D008297:Male; D012377:Rodentia / Q000378:metabolism / Q000502:physiology*; D013077:Sperm Head / Q000378:metabolism / Q000502:physiology* / Q000648:ultrastructure; D013084:Sperm-Ovum Interactions; D013438:Sulfhydryl Compounds / Q000378:metabolism; D015044:Zona Pellucida / Q000378:metabolism / Q000502:physiology* / Q000648:ultrastructure
chemical_list: D003598:Cytoskeletal Proteins; D013438:Sulfhydryl Compounds