Appearance of collagen fibers in the cerebral vascular wall following subarachnoid hemorrhage.

Abstract

Ultrastructural examinations of the cerebral vascular wall following subarachnoid hemorrhage (SAH) demonstrated that collagen fibrils developed in the muscle layer near the adventitia in the early stage of SAH and increased in number and volume with time. These findings suggest that accelerating factors of collagen synthesis in the muscle layer may be released from the adventitial side, and collagen synthesis is induced by extravascular factors. The changes of collagen volume with time suggest collagen to be an important phenomenon of persistent vasospasm after SAH. Histoimmunological studies showed that increased collagen fibers in the tunica media were mainly type III collagen, implying that cerebral vasospasm may be related to chemical inflammation.