Tissue culture studies of interactions between axons and myelinating cells of the central and peripheral nervous system

This chapter summarizes recent tissue culture observations on neuronal influences on the proliferation and functional expression of nonneuronal cells. It emphasizes the importance of extracellular matrix production in the development of full functional expression of Schwann cells. The evidence that the axonal signal for Schwann cell proliferation involves an axonal membrane-associated heparan sulfate proteoglycan is reviewed in the chapter. It also reviews very recent evidence that direct axonal contact influences the proliferation of oligodendrocytes obtained from mature rat spinal cord. Nonneuronal cells are frequently studied in isolation in tissue culture; however, the studies described in the chapter indicate the importance of observations on cultures allowing direct interaction between neurons and nonneuronal cells. The studies of Schwann cells grown with neurons in long-term tissue culture have established that these Schwann cells synthesize and release a variety of extracellular matrix materials. These materials include types I, III, IV, and V collagen, as well as the basal lamina components, laminin, entactin, and a heparan sulfate proteoglycan.