Alteration in vomeronasal system anatomy in alcelaphine antelopes: correlation with alteration in chemosensory investigation.

Ruminants typically have an incisive papilla and incisive ducts located on the hard palate just behind the dental pad which are involved in transferring fluid-borne stimulus material from the oral cavity to the vomeronasal organs (VNOs) during flehmen. This behavior in males is presumably involved in the detection of chemosensory cues in female urine which indicate sexual status. Two species of alcelaphine antelopes, topi and Coke's hartebeest, were found to lack the incisive papilla and incisive ducts constituting the oral connection to the VNOs. This distinctive anatomical feature is complemented in these species not only by lack of flehmen behavior, but also a de-emphasis on chemosensory interest in female urine during sexual encounters. The common wildebeest, which is also an alcelaphine antelope, lacks the incisive papilla, but has small incisive ducts. Wildebeest males do perform flehmen to urine from females. However, during flehmen in the wildebeest, intermittent nostril licking apparently delivers the stimulus material to the VNOs via the nasal route, possibly compensating for reduced oral access to the VNOs. These observations on alcelaphine antelopes would appear to represent a unique feature among the world's ruminants.