The influence of nerve fibres on Schwann cell migration investigated in tissue culture

Abstract

A study of tissue cultures prepared from rabbit sciatic nerves was undertaken to determine the effect of reinnervation on the amount of cell outwandering from nerves undergoing Wallerian degeneration. For this purpose, 25 and 100 days before culturing, some nerves were completely severed and reinnervation prevented, while others were crushed, allowing rapid reinnervation. It was found that reinnervation profoundly diminished the amount of Schwann cell outwandering, in comparison with the outwandering from non-reinnervated nerves. This effect extended only a few cm. distally to the lesion when the nerve was cultured 25 days after interruption, but by 100 days extended much farther towards the periphery. In the region a few cm. distally to the lesion the intensity of the effect was little if at all increased by prolonging the period between operation and culture. The effect was confirmed in reinnervated nerves prepared by complete severance and subsequent suture. Reinnervation influences only the Schwann cells in this way; the outwandering of cells other than Schwann cells did not differ significantly between reinnervated and non-reinnervated nerves. The total cell population within the nerves, estimated from histological sections, is not detectably affected by reinnervation. The interpretation suggested is that a specific adhesion develops between Schwann cells and nerve fibres, and this prevents the migration during tissue culture of a proportion of the Schwann cells.