[Morphologic aspects of the vestibular nerve of the chinchilla].

A quantitative study was made of the number of fibers, their diameters and patterns of distribution in 14 ampullar nerves of chinchilla. The nerves were processed for osmium staining, embedded in plastic and cut serially in 1-micron-thick sections for histologic evaluation. Quantitative evaluation of nerve-fiber characteristics was made with the aid of a laboratory computer and specific programs. The number of the nerve fibers ranged between 1,877 and 2,175. The diameters of the fibers could be as large as 8 microns. The fibers between 2 and 2.5 microns were the most abundant, representing 29.6% of the fiber population. The distribution of fibers in the cristae was size-dependent: 80% of the thin fibers were located at the ends of the nerves, while most of the thick fibers were distributed through the central and intermediate areas.