[Ultrastructural characteristics of branch sphincters and precortical arteries in the rabbit pial arterial system].

Structural peculiarities of pial arteries and their active microvascular segments-sphincters in offshoots and precortical arteries have been investigated, using electron and light microscopy. Our studies have revealed that these vascular segments, which can independently change their lumen, possess multiple myoendothelial junctions, as well as neuro-muscular contacts. This gives evidence of their independent responses that might be determined by structural peculiarities and innervation of their walls.