Histological evidence of specialized microcirculation of the endolymphatic sac.

A specialized type of blood vessel is demonstrated within the dense soft tissue areas of the vestibular aqueduct and vascular channels of the surrounding bone, including the paravestibular canaliculus (PVC). The vessel wall is formed by the collagen-smooth muscle bundles of these areas. The lumen of these vessels is irregular, and segments appear to be closed by apposition of the bundles. The vessels are continuous with the capillaries of the endolymphatic sac. It is not clear whether they are on the venous side of the capillary system, or on the arterial side and might possibly be part of an arteriovenous anastomoses system. Their possible role in some cases of Meniere's disease must be considered.