title: Observations on the reproductive physiological status of mature herd bulls, bachelor bulls, and young bulls in the hippopotamus. Hippopotamus amphibius amphibius Linnaeus.
mesh_terms: D000367:Age Factors; D000818:Animals; D001188:Artiodactyla / Q000502:physiology*; D001699:Biometry; D004822:Epididymis / Q000033:anatomy & histology; D006321:Heart / Q000033:anatomy & histology; D008297:Male; D009929:Organ Size; D012671:Seminiferous Tubules / Q000033:anatomy & histology; D013094:Spermatozoa; D013737:Testis / Q000032:analysis / Q000033:anatomy & histology; D013739:Testosterone / Q000032:analysis
chemical_list: D013739:Testosterone