We have examined the expression of a gap junction protein, connexin32
(Cx32), in Schwann cells and oligodendrocytes. In peripheral nerve, Cx
32 is found in the paranodal myelin loops and Schmidt-Lanterman incisu
res of myelinating Schwann cells, and the levels of Cx32 protein and m
RNA change in parallel with those of other myelin-related genes during
development, Wallerian degeneration, and axonal regeneration. In the
central nervous system, Cx32 is found in oligodendrocytes and their pr
ocesses, but not in compact myelin, and the levels of Cx32 protein and
mRNA increase during development in parallel with those of the other
myelin genes. Thus, Cx32 is expressed as part of the myelinating pheno
type of both Schwann cells and oligodendrocytes, indicating that this
gap junction protein plays in important role in the biology of myelin-
forming cells.