Electron microscopy of trypsin-digested peripheral nerve myelin.
Sciatic nerves from mice were removed and soaked in either PBS (phosphate buffered saline) or PBS plus I% trypsin (Sigma Type III) for various periods of time. Specimens were soaked at either room temperature or 37-degrees C at pH's ranging from 7.5 to 8.0. The epineural and perineural sheaths were split to allow the trypsin to penetrate the nerve. Tissue was prepared for electron microscopy by fixation in cacodylate buffered formaldehyde-glutaraldehyde solutions, post-fixed in OSO4 and embedded in Epon 812 or in glutaraldehyde-urea resin without osmication. After four h incubation at 37-degrees C or eight h at room temperature, the basement membranes of the Schwann cells became fragmented and detached and the myelin intraperiod band lost some density. After 18 h, myelin with swollen intraperiod bands displaying a loss of electron density and split main period bands was noted adjacent to normal myelin. Other areas had been transformed into vesicles indicating that the membranes of these vesicles appeared to have been derived from the detachment of both the intraperiod and main period bands within the myelin. Evidence is presented for the presence of trypsin digestable proteins in both the main period and intraperiod bands of peripheral nervouse system myelin.
D000818:Animals; D001485:Basement Membrane / Q000648:ultrastructure; D002384:Catalysis; D051379:Mice; D008854:Microscopy, Electron; D009186:Myelin Sheath / Q000648:ultrastructure*; D009419:Nerve Tissue Proteins; D010525:Peripheral Nerves / Q000648:ultrastructure*; D012583:Schwann Cells / Q000648:ultrastructure; D014357:Trypsin
D009419:Nerve Tissue Proteins; D014357:Trypsin