The epipharyngeal bursa in the Rhinocerotidae



The mammalian bursa epipharyngea commonly presents as an insignificant mucosal recess, not always recognisable macroscopically. In some mammalian forms, however, it is developed into an obtrusive diverticulum (sacculus epipharyngeus) extending caudally from the epipharynx between the cranial base and the pharynx roof. Among the Rhinocerotidae such an epipharyngeal saccule has been recorded for Ceratotherium simum. Herein it is described for the first time in Rhinoceros unicornis, Diceros bicornis and Didermocerus sumatrensis. Its tonsillar nature is established on morphological and histological grounds.