One important outcome of the work on the expression of genes in developing embryos is sure to be knowledge that can help preventing birth defects. Just as promising 1. ______ is the possibility of unravel the complicated wiring 2. ______ of the brain. A mechanic gets valuable insight how an 3. ______ automobile works by rebuilding car engines; similarly, neuroscientist can learn how the brain functions from 4. ______ the way it is put together. The next step pursuing the 5. ______ goal is to find out how the blueprint genes, the homeobox genes, control the expression of other genes that create the valves and pistons of the working cerebral engine. The protein encoded by the later genes could change the 6. ______ stickiness of the cell surface, the shape of the cell or its metabolism to create the characteristics peculiar to, say, neurons or neural-crest cells. Surface proteins may be the mechanism, whereby similar programmed cells stick 7. ______ together to form specific structures; they might also sense the local environment to help the cell decide what is to do. 8. ______ Clarifying those mechanisms will engage the best talents in embryology and molecular biology for some times to come. 9. ______ What is perhaps the most intriguing question of all is if the 10. ______ brain is powerful enough to solve the puzzle of its own creation.