Evidence for developmental plasticity of the rubrospinal tract. Studies using the North American opossum.

Using axonal tracing techniques we have shown that rubral axons are capable of growing around lesions of the rubrospinal tract during early stages of development in the North American opossum and that a critical period for such growth exists. The opossum was employed for study because it is born in a very immature state 12-13 days after conception and the entire development of its rubrospinal tract occurs postnatally.