Clinical implications of rhinoceros reproductive tract anatomy and histology

Reproductive tracts or tissues from five male black rhinoceroses (Diceros b icornis), two male white rhinoceroses (Ceratotherium simum), two male one-h orned Asian rhinoceroses (Rhinoceros unicornis), seven female black rhinoce roses, and six female white rhinoceroses from multiple institutions were ex amined to characterize their anatomy and histology. Some observations and m easurements were obtained from in situ tracts of intact animals before or d uring necropsy. Formalin-fixed tissues were dissected and examined histolog ically. Retrospective reproductive data from each rhinoceros was obtained f rom the institutions of origin. Reproductive histology of these species was similar to that of other mammals. Male accessory gland structure varied am ong species, and the Asian rhinoceros epididymis was more loosely attached and had larger duct diameters than did the epididymides of the African spec ies. Although histology was typically mammalian, rhinoceros reproductive mo rphology combined chacteristics of several different mammals. Defining this unique morphology of rhinoceroses may help in understanding their reproduc tive physiology and will effect the development of appropriate reproductive techniques.