arachnoid granulations

tufted prolongations of pia-arachnoid, composed of numerous arachnoid villi that penetrate dural venous sinuses and effect transfer of cerebrospinal fluid to the venous system. At advanced age these are more numerous and tend to calcify. Syn: granulationes arachnoideales [NA], arachnoidal granulations, pacchionian bodies, pacchionian corpuscles, pacchionian glands, pacchionian granulations.