In the adult rat chamber model for PNS regeneration, the two stumps of a resected sciatic nerve are inserted into opposite ends of a cylindrical silicone tube leaving a 10 mm, 25 u1 gap between them. In a defined sequence--fluid exudate accumulation, acellular matrix formation, cell immigration and axonal regrowth- a nerve structure forms de novo in the chamber and sensory and motor recoveries eventually take place. This research will complete the development of a continuous perfusion system for the experimental administration of exogenous agents, in particular: neuronotrophic factors, growth factors for Schwann and other cells, and neurite-promoting extracellular matrix components.