TRANSPLANTATION OF CENTRAL NERVOUS-TISSUE - AN INTRODUCTION WITH RESULTS AND IMPLICATIONS

Abstract

Some historical data and results of a study on CNS transplantation are presented. Pieces of hippocampal tissue from embryonic or early postnatal rats were transplanted to different parts of the brain of littermates or adult rats. About 2/3 of the transplants were recovered after survival times ranging from 4 days to 2 yr, and their cytological organization and intrinsic connections were monitored by cell and fiber stains and histochemical methods (AChE [acetylcholinesterase] staining and Timm sulfide silver method). Comparison with both a normal and a lesioned control material revealed that in most transplants the tissue had developed as it does when left in situ in the donor brain, but deprived of its major afferent connections. In several instances there was evidence of a major exchange of connections between the transplants and host brains. The conditions needed for this to occur appeared to involve growth stimulation of host brain fibers by transection (host to transplant) and denervation of host neuropil (transplant to host). In cases where these conditions are met, the use of transplants may have future implications in attempts to repair lesions in the CNS.