The vomeronasal (Jacobson's) organ in adult humans: frequency of occurrence and enzymatic study.

The vomeronasal system in adult humans has commonly been regarded as absent or vestigial, but recently it was found to be more common than previously reported. In this study, a search for the frequency of occurrence of the vomeronasal organ (VNO) was performed by examining the nasal septae of 200 adult patients. The frequency of occurrence was found to vary according to the method of examination. By anterior rhinoscopy, large pits and even deep grooves lined by glistening mucosa were visible in 16% of the people examined. Using nasal endoscopes this ratio increased to 76%. After receiving informed, written consent, from 13 patients undergoing endonasal surgery under general anaesthesia, one VNO was dissected out. Specimens were examined histologically and histochemically for succinic dehydrogenase and alkaline phosphatase enzymes. One specimen was processed for transmission electron microscopy. Two morphologically distinct cell types were differentiated. One cell type was previously suggested to have some of the features associated with nerve cells and could have a sensory function. A possible function for the VNO is postulated.