title: Ultrastructural observations of boar spermatozoa penetrating zona-free hamster eggs.
mesh_terms: D000177:Acrosome / Q000648:ultrastructure; D000818:Animals; D006224:Cricetinae; D005260:Female; D005306:Fertilization; D005307:Fertilization in Vitro; D008297:Male; D008647:Mesocricetus; D010063:Ovum / Q000648:ultrastructure*; D013084:Sperm-Ovum Interactions; D013094:Spermatozoa / Q000648:ultrastructure*; D013552:Swine