Abstract
A detailed map of the vestibular nuclear complex of the guinea pig has been established by Gstoettner and Burian (1987), using cytoarchitectonic (cresyl violet staining) and fiberarchitectonic criteria. However, the exact borders between the different subdivisions are not always evident in Nissl stained sections. In the present study, serial sections of the vestibular nuclei of the guinea pig were stained to visualize acetylcholinesterase (AChE) activity, and compared with corresponding sections stained with cresyl violet. All of the subdivisions of the vestibular nuclear complex previously described are more readily distinguished in AChE than in Nissl preparations. The AChE reactivity also shows that the medial vestibular nucleus extends more rostrally than previously described. Furthermore, it questions whether the area classically referred to as the rostral pole of the descending vestibular nucleus belongs to the descending vestibular nucleus or to the lateral vestibular nucleus (LV). Finally, a morphometric analysis performed on cresyl violet stained sections shows that (1) in the caudal LV, the neurons of the ventromedial extension are smaller than those of the dorsolateral extension and that (2) in the rostral LV, the ventromedial division contains a larger ratio of smaller neurons than the dorsolateral one.