| Abstract: | Tissue containing the attachment of nerve roots to the spinal cord was dissected from seven rats perfused with buffered aldehydes. Both dorsal and ventral roots were obtained from all cord levels. All tissues were prepared routinely for electron microscopy. The outer layers of the root sheath are homologous with the outer layers of the pia mater and are essentially continuous with it. The inner layers of the root sheath, which are a structurally modified and centrally directed continuation of the perineurium across the subarachnoid space, terminate as an open-ended tube near the junction of the peripheral and central nervous systems. Here there is direct continuity between the endoneurial connective tissue space and the pial connective tissue space. The latter, in turn, communicates directly with the subarachnoid space through fenestrations between pial cells. The relationship of this to certain clinical manifestations is briefly discussed. |
