Pulmonary surfactant-like multilamellar bodies in human arachnoid villi.

Human arachnoid villi adequately treated with tannic acid before osmication ultrastructurally disclosed highly ordered multilamellar bodies in all of the 6 subjects studied. The multilamellar bodies were varied considerably in size and shape, but often showed a fingerprint-like appearance. They were found in the intercellular space, extracellular cisterns or microcores and within the cytoplasm of arachnoid cells. The number of lamellae in a single lamellar body ranged from 3 to 20, and the periodical width of the lamellae was approximately 5.0 nm. The outermost lamella sometimes showed a direct continuity with the adjacent plasma membranes of the cytoplasm or mitochondria. As multilamellar bodies were ultrastructurally quite similar to pulmonary surfactant, they were assumed to be related to the lubricated flow or absorption of the cerebrospinal fluid.