Description: (from the abstract) Apoptotic cell death occurs in the nervous system during normal and in pathological situations. The PI's preliminary data indicate that apoptosis has a major role in the ES cell graft after transplant into the injured rodent spinal cord. The extent of cell death underlie this process are currently unknown. The goal of this proposal is to apoptotic cell death of ES cell-derived neural lineage cells (ESNLCs). In relevant stages of development. In the second, he will characterize the apoptosis-inducing activity of the syrinx fluid which accumulates in the spinal apoptosis-inducing activity, and determine the changes in this activity as a function of time post-injury. Third, he will utilize the paradigms developed in to the molecular mechanisms of apoptosis and to develop cell clines that are resistant to apoptosis. These experiments should help to define the optimal molecules that are responsible for apoptosis induction seen after the success of ESNLC transplants.