Genetic Mechanisms in the Localized Initiation of Differentiation

This discussion deals with a limited part of the problem of differentiation. As a whole the problem involves both the initiation and the progression of a sequence of events which lead to the appearance in development of specific structures and functions. Genes partake directly or indirectly in all the reactions which are involved in differentiation. While these reactions are distinguished from those occurring in differentiated cells by their progressive, nonequilibrium nature, by themselves these reactions may be thought of as basically similar to those in cells with more stationary life processes. But a peculiarity of developmental reactions is the fact that they seem to have a beginning. A unique situation arises, at a specific region of the developmental system. This unique situation then leads to further developmental newness. We shall be concerned with the role of genes in the localized initiation of newness.