Annals of neurology
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Transplants of embryonic central nervous system tissue have long been used to study axon growth during development and regeneration, and more recently to promote recovery in models of human diseases. Transplants of embryonic substantia nigra correct some of the deficits found in experimental Parkinson's disease, for example, by mechanisms that are thought to include release of neurotransmitter and reinnervation of host targets, as well as by stimulating growth of host axons. Similar mechanisms appear to allow intraspinal transplants of embryonic brainstem to reverse locomotor and autonomic deficits due to experimental spinal cord injuries. ⋯ Transplants of fetal spinal cord may also contribute to behavioral recovery by rescuing axotomized host neurons that otherwise would have died. Electrophysiological and behavioral investigations of functional recovery after intraspinal transplantation are preliminary, and the role of transplants in the treatment of human spinal cord injury is uncertain. Transplants are contributing to our understanding of the mechanisms of recovery, however, and are likely to play a role in the development of rational treatments.