Central nervous system structures labelled from the testis using the transsynaptic viral tracing technique

In the present study, the transneuronal transport of neurotrophic virus tec hnique was used to identify cell groups of the spinal cord and the brain th at are transsynaptically connected with the testis. Pseudorabies virus was injected into the testis and after survival times of 3-6 days, the spinal c ord and brain were processed immunocytochemically using a polyclonal antibo dy against the virus. Virus-infected perikarya were detected in the pregang lionic neurones of the spinal cord (T10-L1, L5-S1) and in certain cell grou ps and areas of the brain stem, the hypothalamus and the telencephalon. In the brain stem, the cell goups and areas in which labelled neurones were pr esent included, among others, the nucleus of the solitary tract, the caudal raphe nuclei, the locus coeruleus and the periaqueductal grey of the mesen cephalon. In the hypothalamus, virus infected perikarya were observed in th e paraventricular nucleus and in certain other cell groups. Telencephalic s tructures containing labelled neurones included the preoptic area, the bed nucleus of the stria terminalis, the central amygdala and the insular corte x. These data identify a multisynaptic circuit of neurones in the spinal co rd and in the brain which may be involved in the control of testicular func tions.