The processes extending from nerve cells are called axons and dendrites. Dendrites receive messages from other cells, while the axon conducts messages often over long distances. Compared to axons, we know far less about dendrites, and little about how the distinctions between the two arise during development. This project extends studies on the molecular identity of a compound believed to be a protein that appears to act specifically as a dendrite-promoting factor. A novel neuronal culture system has been established to test the effects of this compound on isolated growing cells. Microscopic analysis of cells along with protein chemistry will be used to assay and isolate the purified molecule. The purification of such a unique factor will have a great impact on developmental neuroscience, and the potential opportunity for further biotechnological development of such a product is very high.