Identification of CNS neurons involved in the innervation of the epididymis: a viral transneuronal tracing study

Cell groups of the spinal cord and the brain transsynaptically connected wi th the epididymis (caput, cauda) were identified by means of the viral tran sneuronal tracing technique. Pseudorabies virus was injected into the caput or the cauda epididymidis, and after survival times 4 and 5 days, the spin al cord and brain were processed immunocytochemically. Virus-labeled neuron s could be detected in the preganglionic sympathetic neurons (lower thoraci c and upper lumbar segments) and following virus injection into the cauda e pididymidis, also in the sacral parasympathetic nucleus (L-6-S-1). Virus-in fected perikarya were present in several brain stem nuclei (lateral reticul ar nucleus, gigantocellular and paragigantocellular nucleus, A5 noradrenerg ic cell group, caudal raphe nuclei, locus coeruleus, Barrington's nucleus, nucleus of the solitary tract, periaqueductal gray) and in the diencephalon (hypothalamic paraventricular nucleus, lateral hypothalamus). At the longe r survival time, some telencephalic structures also exhibited virus-labeled neurons. The distribution of infected neurons in the brain was similar aft er virus injection into the caput or cauda epididymidis; however, earlier o nset of infection was observed after inoculation into the cauda. The presen t findings provide the first morphological data on a multisynaptic circuit of neurons innervating the epididymis and presumably involved in the contro l of epididymal functions. (C) 2001 Elsevier Science B.V. All rights reserv ed.