The shaping of tissues in embryos.

fifter the egg of a higher organism A is ferti l ized it divides into many / I thousands of cells that arrange themselves into the tissue layers of the embryo. Understanding this elaborate process of embryonic development is one of the outstanding and most difficult problems challenging biologists today. The problem is so complex that it must be broken down into smaller problems before investigation can yield instructive solutions. Therefore in our own work we set out to address the general question of how tissues are shaped in the embryo by analyzing the formation of a single embryonic tissue: the neural plate, the earliest precursor of the central nervous system. The organism we