Cochlear nuclear complex of mice.

Abstract

Using serial sections stained with luxol fast blue-cresyl violet, the cochlear nuclei of CBA/J mice were parcellated into the same cytoarchitectonic areas and layers that Osen (1969) used in cats. Within the spherical cell areas, the distribution of Nissl substance is more reliable than soma shape in identifying the spherical cells. The area of large spherical cells is extremely small in CBA/J mice but does contain significantly larger neurons than the small spherical cell area. In Golgi preparations, bushy cells are found in all areas of the ventral cochlear nucleus except in the octopus cell area and granule cell layer. They are more numerous anteriorly than posteriorly and details of their morphology are quite variable. Stellate cells are found throughout the ventral cochlear nuclei but are present in greatest numbers in the multipolar cell area; they are rare in the large spherical cell area and octopus cell area. Because size, soma morphology, and dendritic arborization vary on a continuum rather than in discrete steps, we have not subcategorized these neurons. Octopus cells are restricted to the posterior, dorsomedial area of the ventral cochlear nucleus. In the central region of the dorsal cochlear nucleus, stellate cells abound and are categorized as vertical, elongate, or radiate cells. In the granule layer of the dorsal cochlear nucleus there are both fusiform and Purkinje-like neurons, so named because of their resemblance to cerebellar Purkinje cells. These Purkinje-like cells differ from fusiform cells in having 1) a smaller cell body, spherical in shape, 2) no basal dendrites, 3) a sagittal dendritic orientation, 4) elaborate dendritic branching, and 5) abundant dendritic spines.