Free Floating Microcultures of Human Fetal Ventral Mesencephalon

327 In the reported clinical trials of human fetal ventral mesencephalic transplants to the brain of Parkinson patients the tissue was transplanted either as small solid pieces or as cell suspensions. In all cases the tissues were implanted immediately after explantation. Delayed surgery and the in vitro maintenance of the tissue prior to trans-plantation would present several advantages. For example, this would allow one to estimate the approximate number of neurons transplanted and to measure dopamine content and tyrosine-hydroxylase (TH) activity in vitro expressing the activity of the cultures. Furthermore tissues in vitro could be treated with various growth factors.