1.   Or, they could have their developmental pathway specified before they begin migrating and then would migrate to the correct sites.

2.   Both funnel through the same developmental pathways, and it is those pathways, which are still not well understood, that hold the secrets to physiology.

3.   Cultures of the cells in the laboratory could be nudged down different developmental pathways to become heart or bone marrow or pancreatic cells.

4.   Each binds to the surface of certain cells and activates a variety of developmental changes that instruct cells how to grow and which developmental pathways to take.

5.   But if they can, they might someday be able to make immature cells in test tubes start down the developmental pathway toward particular brain cell types.