[Morphological study on innervation of the cerebrospinal blood vessels. I. Cerebral blood vessels].

The distribution of nerve fibers in the cerebral blood vessels was studied by a catecholamine histofluorescence method, acetylcholinesterase (AChE) staining and immunohistochemistry. The ultrastructure of the terminal boutons in the vessel wall was also studied. In the adventitia of the cerebral artery, green fluorescence aminergic fibers and brownish AChE-positive (probably cholinergic) fibers were observed. In contrast, the cerebral venous system showed no AChE-positive fibers. The highest density of aminergic fibers were found in the dural sinus and the second highest in the internal cerebral vein. Serotonin immunoreactive nerve fibers were found along small intraparenchymal blood vessels such as perforating arteries in the brain stem, and arterioles and venules in the cerebral cortex. Under ultrastructural observation, a serotonin immunoreactive terminal was demonstrated in conjunction with the basement membrane of the capillary.