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Washington University Experience | NEOPLASMS - CRANIAL AND PARASPINAL NERVEs | Perineurioma, Intraneural | 5D1 Perineurioma (Case 5) EM 011 - Copy

5D1,2-Ultrastructural studies confirm the loss of large and small myelinated axons but also demonstrate the loss of large numbers of unmyelinated axons. There are scattered actively degenerating axons and numerous bands of Bungner. Schwann cells are surrounded by thick spindled processes, which are delicate, aggregating in groups. These processes show a prominent basement membrane, as one might see with bands of Bungner but, in distinction, have large numbers of pinocytotic vesicles (arrow, 5D2) and tight-junctions (arrowhead, 5D2) as expected in perineurial cells. These structures vary in distribution between fascicles.

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