GROSS-ANATOMY OF THE REPRODUCTIVE-TRACT OF FEMALE BLACK (DICEROS-BICORNIS-MICHAELI) AND WHITE RHINOCEROS (CERATOTHERIUM-SIMUM-SIMUM)

Reproductive tracts were collected from three black rhinoceros and two white rhinoceros at necropsy. All females were nulliparous, except for one primiparous white rhinoceros. The animals ranged in age from 7 days to 28 years. All nulliparous animals had a constriction in the vaginal canal, which appeared to be a hymen. The primiparous female had only remnants of a hymen. The total length of the tract averaged 102 cm in three adult animals (greater-than-or-equal-to 21 years old). The distance from the vulva to the external cervical os averaged 40 cm in these animals. The endometrium of a 28-year-old nulliparous black rhinoceros and a 27-year-old nulliparous white rhinoceros exhibited signs of hyperplasia, whereas this condition was not present in the other animals. It is not known if this condition was related to the fertility of these animals. The cervix of the rhinoceros was firm, and the lumen followed a very tortuous path through eccentric rings of tissue. Visual examination of the ovaries revealed the presence of surface follicles on the ovaries in both species. The overall size of the reproductive tract, especially the vagina and uterine horns, and the extremely tortuous cervical lumen will present obstacles that must be overcome when developing artificial insemination and embryo transfer procedures for use in rhinoceros.