Relationship between granule-containing cells and blood vessels in the rat autonomic ganglia

Granule-containing (GC) cells and related blood vessels in the superior cervical ganglion and the pelvic plexus of the rat were examined by light and electron microscopy of serial thin sections. In the superior cervical ganglion, GC cells formed many clusters of more than 20 cells. These clusters were supplied with dense networks of fenestrated capillaries, while the ordinary ganglion cells had continuous capillaries distributed more sparsely. Several continuous capillaries diverged from the networks in the GC cell clusters to join with capillaries around the ganglion cells. In the pelvic plexus, continuous capillaries with well-developed pericytes were distributed similarly around the GC cells and the ganglion cells. Dense networks of fenestrated capillaries in the clusters were never seen. Based on these observations, the physiological significance of the GC cells was discussed.