Dual adrenergic and cholinergic innervation of the cerebral arteries of the rat. An ultrastructural study.

Abstract

The innervation of the anterior cerebral artery of the rat was examined by electron microscopy and by the fluorescence method for localizing adrenergic nerves. Two groups of axon bundles were associated with the artery; one at the outer margin of the adventitia ( periadventitial bundles) and the other within the adventitia or at the adventitia-media border ( adventitial bundles). Periadventitial bundles consisted of nonmyelinated axons (0.1-2µ diam), some of which contained synaptic vesicles; in some bundles, myelinated axons were seen. Adventitial axons often contained many synaptic vesicles and were free of Schwann cell sheath in areas appose..