title: Ultrastructure of double-headed spermatozoa in bulls and stallions.
mesh_terms: D000818:Animals; D002417:Cattle; D002462:Cell Membrane / Q000648:ultrastructure; D002467:Cell Nucleus / Q000648:ultrastructure; D004247:DNA / Q000378:metabolism; D006736:Horses; D008297:Male; D008854:Microscopy, Electron; D008870:Microtubules / Q000648:ultrastructure; D008928:Mitochondria / Q000648:ultrastructure; D013094:Spermatozoa / Q000378:metabolism / Q000648:ultrastructure*
chemical_list: D004247:DNA