NEURONAL ARCHITECTURE OF THE DORSAL NUCLEUS (COCHLEAR NUCLEUS) OF THEFROG, RANA-PIPIENS PIPIENS

The neuronal architecture of the dorsal nucleus of the Northern leopar d frog (Rana pipiens pipiens), which is a homolog of the cochlear nucl eus of mammals and birds, was investigated. Our study showed that the frog dorsal nucleus contains a number of morphologically distinct cell types that are discernible in terms of the cellular architecture as d erived from Nissl-stained material and in terms of the dendritic profi le as revealed by horseradish peroxidase-filled single neurons. These cell types are bushy cells, bipolar (or fusiform) cells, octopus cells , stellate cells, giant cells, radiate (or round) cells, and a variety of small cells. The different cell types occupy different regions of the nucleus. Therefore, our results suggest that the dorsal nucleus sh ould no longer be considered to be a uniform nucleus containing a homo geneous population of neurons. Homologies of these cell types with tho se described in other vertebrate species, including mammals, are propo sed. (C) 1996 Wiley-Liss, Inc.