The project will use multipotent neural stem cells as starting material. These cells, which reside in the central nervous system, will be isolated from the developing brains of five- to eight-week-old human fetuses and expanded to large numbers under stimulation by growth factors. The project seeks to identify precursors of midbrain dopamine neurons using cellular markers of developing dopaminergic neuroblasts. Candidate cell lines will be tested for their capacity to differentiate into mature dopamine neurons, and the cells' ability to survive, grow, and integrate into the brain will be investigated following transplantation to the striatum in rats with experimental Parkinson's disease. The functional properties will be analyzed both electro-physiologically and biochemically, and in a broad range of neurological tests. The cells will be developed under such conditions that will allow their use in future clinical trials.