Sympathetic neurons in the cat spinal cord projecting to the stellate ganglion

Horseradish peroxidase (HRP) was injected into the stellate ganglia of anesthetized cats. After a 2‐day survival time the spinal cord was processed for the HRP reaction to study the distribution of the preganglionic neurons which project to the stellate ganglia. HRP‐labeled neurons in the cord were located exclusively on the side ipsilateral to the injected stellate ganglia and were concentrated in four distinct areas: (1) intermediolateral cell column (78.2%), (2) lateral funiculus (18.5%), (3) intercalated area and (4) central autonomic area (3.3% for the latter 2 areas). Their distribution pattern in the very rostral pole of the thoracic sympathetic preganglionic cell column was different from the typical thoracic pattern in that a greater proportion of the cells were located in the lateral funiculus, and a few labeled cells were observed in the ventral horn. Longitudinally, a wide range (C8‐T8) of spinal cord levels projected to the stellate ganglia, with a peak at the T2 level. These observations infer that a large population of axonal processes of sympathetic preganglionic neurons traveled several segments of the spinal cord through an intraspinal pathway before exiting a particular ventral root.