Verstibular Efferent Neurons of Otolith Organs in Monogolian Gerbils

The different results of the morphological studies of the efferent neurons in vestibular system have been reported according to the different animals and methods of investigation. Locations, projectional patterns and ell ount of the vestibular efferent neurons of the otolith organs in the brainstem of 20 Mongolian gerbils were investigated with the use of retrograde transport of horseradish-peroxidase (HRP) by scratch method. The neurons were located dorsal to facial genu and ventro-medial to vestibular nucleus (group Ⅰ), in reticular formation ventral to facial genu (group Ⅱ) and ventro-medial to descending vestibular nucleus (group Ⅲ). Group Ⅰand group Ⅱ were located bilaterally, but neurons of group Ⅲ were observed only in ipsilateral side. Labeled efferent neurons were more abundant in contralateral side than ipsilateral side in bilaterlly labeled groups.ope