The proposed project provides a means of studying the unique process of neurogenesis and nerve cell replacement that takes place in the mammalian olfactory system. Chemical and axotomy procedures will be used to induce degeneration of sensory neurons. Subsequent neurogenesis and recovery will be studied using quantitative methods to determine the capacity and limits of this unique process. In addition, an assessment will be made of the importance of target tissue (olfactory bulb) for the replacement of olfactory neurons and the ability of these replacement neurons to re-establish functional connections with the central nervous system. It is expected that data from the proposed study will produce new information which could prove helpful in improving recovery following nerve cell injury. Eventually these studies may lead to methods which could help to repair damaged pathways in the human central nervous system.