Collagenosis in Wallerian degeneration depends on peripheral nerve type

In the mature rat we determined the extent of peripheral nerve collagenosis in response to Wallerian degeneration and examined whether or not nonfibroblastic elements such as Schwann cells were important. Collagen was estimated as the hydroxy-proline content of normal and axotomized nerve fascicles after single or double crush lesions of both myelinated and unmyelinated nerves. Crushed unmyelinated nerve produced two to four times more collagen relative to control nerve than did the sciatic nerve. The nature of the interaction between two successive crushes was different in the two nerves. These results suggest that the degree of collagen fibrillogenesis occurring in Wallerian degeneration is dependent on peripheral nerve type and that the presence of myelin is not necessary for collagen fibrillogenesis.