Location of lumbar preganglionic sympathetic neurones in the cat.

In the cat the distribution and projection of lumbar (L1-L4) preganglionic sympathetic neurones (PSNs) has been investigated with the horseradish peroxidase (HRP) technique. Following an HRP-injection into a lumbar sympathetic trunk ganglion, PSNs were found in the ipsilateral spinal cord in lamina VII, specially in its lateral and intermediate parts. In the medial region HRP positive cells were more frequently observed when the central, cut end of the ramus communicans albus was placed into HRP. HRP injection into the coeliac and lower mesenteric ganglia labelled lateral PSNs, but rarely medial ones. In the cranio-caudal direction, the PSNs projected over several segments via intraspinal and extraspinal pathways.