CNS CELL GROUPS INVOLVED IN THE CONTROL OF THE ISCHIOCAVERNOSUS AND BULBOSPONGIOSUS MUSCLES - A TRANSNEURONAL TRACING STUDY USING PSEUDORABIES VIRUS

Transneuronal tracing techniques were used to identify spinal and brai nstem neurons involved in the control of perineal muscles in the male rat. Two penile muscles, the bulbospongiosus and ischiocavernosus musc les, were injected with Bartha's strain of pseudorabies virus. After s urvival periods of 2, 4, and 5 days, the rats were killed and viral la beled neurons identified by immunohistochemistry. After a 2 day surviv al period, only pudendal motoneurons were labeled. More spinal and bra instem neurons were labeled at longer survival times. Putative spinal interneurons were found from T13 to S1. Large numbers of neurons were found in the lateral horn of the T13-L2 and L6-S1 segments which conta in sympathetic and parasympathetic preganglionic neurons, respectively . However, retrograde labeling experiments verified that very few of t he viral neurons were preganglionic neurons. Other labeled neurons wer e found in the intermediate cord, especially around the central canal. Relatively few labeled neurons were seen in the dorsal or ventral hor n. In the brainstem, consistent labeling was seen in the ventrolateral medulla, raphe pallidus, and magnus, the A5 and locus ceruleus noradr energic cell groups, Barrington's nucleus in the pontine tegmentum, th e periaqueductal gray, and the paraventricular nucleus of the hypothal amus. The transneuronal labeling was consistent with what is currently known of the central nervous system (CNS) control of the perineal mus cles. (C) 1996 Wiley-Liss, Inc.