[Histochemical study of the vasomotor innervation of the internal carotid artery basin]

In the dog, the internal carotid artery and its branches were found to have a well developed nervous plexus with two kinds of nerve fibers: containing either active cholinesterase or catecholamines. In various segments of the basin, both the cholinergic and the adrenergic nerve fibers reveal structural and topographical differences depending on the structural and functional features of the vascular wall. The adrenergic and cholinergic nerve fibers are mainly situated in the adventitia of the internal carotid artery forming a terminal nervous plexus in deep portions, while in the vasa vasorum and in the siphon region they are terminated also in superficial layers of muscular coat. The data obtained suggest that the vasomotor effects of the sympathetic and parasympathetic nervous systems are most obvious in the intracranial part of the internal carotid artery, in the region of convolution, and in the adjacent portions of the artery situated within the cavernous sinus.