The leptomeninges, consisted of pia mater and arachnoid, cover the surface of brain parenchyma. Leptomeningeal cells produce a number of biologically active proteins, including prostaglandin-D synthase, cyclooxygenase-1, -2, insulin-like growth factor-II, insulin-like growth factor-binding proten-2, and apolipoprotein E, released into the cerebrospinal fluid. The involvement of leptomeninges in neurotrophic, scavenging, and transport activities as well as inflammatory responses, associated with the brain, is reviewed.
Biomedical Reviews 1999; 10: 31-36.