[Neural circuit of the cervical sympathetic nervous system with special reference to input and output of the cervical sympathetic ganglia: relationship between spinal cord and cervical sympathetic ganglia and that between cervical sympathetic ganglia and their target organs].

Using anterograde labeling technique with Phaseolus vulgaris leucoagglutinin (PHA-L), we demonstrated the arborization pattern of a single preganglionic axon in the superior cervical ganglion (SCG) and stellate ganglion (STG). These axons expanded in the longitudinal direction, but not for transverse direction. Segmental relationship was identified between the spinal cord and STG, as seen between spinal cord and sympathetic ganglia in the thoraco-lumbar region, but we did not find any segmental relationship between the spinal cord and SCG. Some sympathetic preganglionic neurons in the lateral horn of the thoracic cord, especially in the intermediolateral nucleus (IML) have nitric oxide synthase (NOS) activity. We demonstrated that SCG neurons, which were heavily innervated by these NOS-positive neurons, tended to innervate organs that have some secretory functional tissues. Finally, we showed that the size of neuronal somata does not correlate with the size of target organs, as has been reported in previous studies. We should consider that there are other factors determining the size of neuronal somata, such as the size of dendritic field or volumes of NGF secretory from target tissues.