The spinal arachnoid villi of the monkeys <i>Cercopithecus aethiops sabaeus</i> and <i>Macaca irus</i>

Abstract

Abstract The spinal arachnoid villi have been studied in the monkey by the examination of serial sections of spinal nerve roots, particular attention being paid to the relations of the arachnoid to the dura mater and to the veins which are regularly applied to the emerging roots. Although the roots vary in their content of specialized arachnoid formations, in many, columns and clusters of arachnoidal cells occupy spaces between collagen bundles in the dura mater. In a few, leptomeningeal tissue extends completely through the dura. In approximately one of each six roots examined, arachnoidal tissue formed part of the wall of and projected into a vein associated with the root. This relationship to veins is considered an especially compelling point in dispelling the doubt which has been cast upon the conception of spinal arachnoid villi as specialized structures.