Morphologic study of the blood vessels of the superior cervical ganglion of the albino rat.

Blood vessels of the rat superior cervical ganglion were examined by both light and electron microscopy. Direct blood supply to the superior cervical ganglion was derived from a capsular plexus of vessels. Intraganglionic vessels were for the most part capillaries. Some of these capillaries appeared dilated and sinusoidal. Although the ganglion did not seem to be densely vascularized, there was sufficient distribution to accommodate the nerve cell bodies of the ganglion. Individual capillaries served groups of neurons. Occasionally, capillary loops could be observed to surround single neuron perikarya. Ultrastructural studies revealed the presence of two types of capillaries. The majority of the capillaries of the rat superior cervical ganglion demonstrated a continuous, non-fenestrated endothelium. Typical junctional complexes were found on abutting endothelial surfaces. Endothelial flaps and microvilli were also observed on the luminal surface of some of the vessels. Numerous micropinocytotic vesicles were observed on both the luminal and abluminal surfaces of the endothelium. A small number of capillaries demonstrated a fenestrated endothelium. In both types of capillaries there was a basement membrane and an extracellular space containing collagen. Perikaryal cytoplasm was separated from the extracellular space by a thick layer of satellite cell cytoplasm.