Histamine-immunoreactive cells in the superior cervical ganglion and in the coeliac-superior mesenteric ganglion complex of the rat.

Histamine-immunoreactive small cells were detected in the superior cervical ganglion and in the coeliac-superior mesenteric ganglion complex of the rat with a specific antiserum produced in rabbits. Most histamine-immunoreactive cells were arranged in clusters, often around small blood vessels. Solitary immunoreactive small cells were also observed and they were easily distinguished from mast cells. The principal nerve cells showed no immunoreactivity to histamine and no histamine-containing nerve fibers were detected in the ganglia by the present method. Due to close morphological similarities, it is concluded that the small immunoreactive cells observed in the present study represent small intensely fluorescent (SIF) cells first detected by formaldehyde-induced catecholamine fluorescence.