Intermediate filaments of Schwann cells.

Intermediate filaments were prepared from distal stumps of rabbit sciatic nerve 5 weeks after nerve section, at which time Schwann cells account for 85--90% of the cell area. A polypeptide of molecular weight 58,000 was the main component of this fraction. An antiserum raised in guinea pig against this polypeptide stained all cells present in the distal stump, as well as Schwann cells and 3T3 cells in culture. The identity of the molecular weight 58,000 polypeptide obtained from distal stumps with vimentin was proved with one and two-dimensional sodium dodecyl sulfate polyacrylamide gel electrophoresis and with immunoautoradiography. It is concluded that the intermediate filament subunit of undifferentiated Schwann cells is vimentin. The possibility that Schwann cells in normal nerve may have another type of intermediate filament besides vimentin cannot be ruled out.