Central distribution of afferent and efferent components of the pudendal nerve in cat.

Central distribution of afferent and efferent components of the pudendal nerve was examined in the cat by the HRP method after applying HRP to the central cut end of the pudendal nerve. Retrogradely labeled neuronal cell bodies were located primarily in the feline homologue of the Onuf's X nucleus, constituting a slender longitudinal cell column in the ventral horn of the S1 and S2 cord segments. The Onuf's nucleus was present constantly from middle S1 to high S2 cord segments, and occasionally extended rostrally to high S1 or low L7, and caudally to middle S2, low S2, or high S3 cord segments. No sex differences were observed in the distribution pattern, number, and soma size of labeled neurons in the Onuf's nucleus. Transganglionically labeled dorsal root fibers were found to terminate ipsilaterally in the lamina I of the dorsal horn at levels of lower lumbar, sacral, and higher coccygeal cord segments and the gracile nucleus, and bilaterally with an ipsilateral predominance in the dorsal commissural gray and laminae III, IV, V, and VI of the dorsal horn at levels of lower lumbar, sacral, and higher coccygeal cord segments. Some labeled dorsal root fibers appeared to end ipsilaterally in the regions where the sacral parasympathetic preganglionic neurons have been shown to be located.