T.R. Shanthaveerappa

Perineural Epithelium: A New Concept of its Role in the Integrity of the Peripheral Nervous System

A multilayered, squamous-celled epithelial cell membrane covering the individual nerve fasciculi of the entire peripheral nervous system ( both voluntary and autonomic) including the sensory and motor end organs has been demonstrated in various species of animals, including man. This membrane is the direct continuation of the pia-arachnoid mater from the central nervous system.Functional significance of this membrane, especially as a diffusion barrier and as a protector of the peripheral nervous system, is briefly discussed.

THE PERINEURAL EPITHELIUM OF SYMPATHETIC NERVES AND GANGLIA AND ITS RELATION TO THE PIA ARACHNOID OF THE CENTRAL NERVOUS SYSTEM AND PERINEURAL EPITHELIUM OF THE PERIPHERAL NERVOUS SYSTEM.

SummaryA multiple layered flat epithelial cell layer covering the sympathetic ganglion chain and its derivatives (e.g. the splanchnic nerves) has been described. This layer is continuous around the grey and white rami communicans and is in turn continuous with the perineural epithelium of peripheral nerves. A capillary plexus and mast cells in this layer have also been demonstrated. This epithelium is shown on the surface of the blood vessel which enters the sympathetic trunk and resembles the leptomeningeal covering of the blood vessels of the central nervous system. The epi- and perineural. and epi- and periganglionic connective tissue layers of the sympathetic system are extremely delicate and minimal in quantity when compared to the epi- and perineurium of peripheral nerves. This paper thus completes the evidence that the whole of the peripheral nervous system and its ganglia (voluntary and autonomic) is isolated from the environment in which it lies and is maintained in an environment similar to or identical with that of the central nervous system.