Separation of sperm pairs and sperm-egg interaction in the opossum, Didelphis virginiana.
D000818:Animals; D005260:Female; D005306:Fertilization; D005307:Fertilization in Vitro; D008297:Male; D008854:Microscopy, Electron; D009865:Oocytes / Q000502:physiology / Q000648:ultrastructure; D009893:Opossums / Q000502:physiology*; D013084:Sperm-Ovum Interactions; D013094:Spermatozoa / Q000502:physiology* / Q000648:ultrastructure