Reactive gliosis in the zone immediately proximal to transection of the sciatic nerve has been inhibited by intraneural injection of mitomycin C, an anti-mitotic agent known to arrest Schwann cell division after transection, crush or demyelination. Mitomycin C-pretreated proximal stumps were subsequently sutured to cellular or acellular autografts (0.5 cm long) and neurite growth into and within the grafts was examined during a 5-week post-operative period. Neurites grew into cellular autografts and became associated with the resident population of Schwann cells within the grafts, to the extent that remyelination was well established in the majority of Schwann cell basal lamina tubes by week 5 post-suture. In marked contrast, very few neurites grew into acellular grafts during this time, and where axons and Schwann cells were seen they tended to be grouped in 'minifascicles'. The results suggest that neurite outgrowth from proximal stumps is dependent upon active Schwann cell participation.