PERIVASCULAR NERVES OF THE HUMAN BASAL CEREBRAL-ARTERIES .1. TOPOGRAPHICAL DISTRIBUTION

In the present study the topographical distribution of the intrinsic n erve plexuses of the basal cerebral arteries in humans was quantified and the relation between vessel diameter and nerve density was investi gated. Whole-mount preparations of various segments of the basal cereb ral arteries from middle-aged patients were stained for protein gene p roduct (PCP) 9.5. The deep nerve plexuses, located at the adventitial- medial border, were quantified by image analysis. Confocal scanning la ser microscopy was used to study nerve plexuses throughout the adventi tia. Transverse cryostat sections were stained for PGP 9.5, tyrosine h ydroxylase and neurofilament, and quantified. The results showed a thr ee-layered configuration of the adventitial nerves. Measurements on wh ole-mounts demonstrated that nerve densities were highest in the poste rior communicating artery (PCom). and next highest in the proximal par ts of the posterior cerebral artery (PCA) and anterior choroidal arter y. There appeared to be no clear relation between nerve density and ve ssel diameter. The measurements on sections confirmed the high nerve d ensities in the PCom and PCA. Tyrosine hydroxylase- and neurofilament- immunoreactivities appeared to demonstrate separate subpopulations of the overall nerve plexuses. representing sympathetic and, possibly, se nsory fibers, respectively. Densities of both subgroups generally foll owed those of PGP 9.5-immunoreactive nerves. Transmission electron mic roscopy suggested motor function of the deep nerve plexuses. The resul ts indicate a stronger neuronal influence on this parr of the cerebral circulation than hitherto reported, It is concluded that human basal cerebral arteries display a topographical distribution of deep perivas cular nerves, and that nerve density is determined by locality rather than by vascular diameter.