Developmental biology is the science connecting genetics with anatomy, making sense out of both. The body builds itself from the instructions of the inherited DNA and the cytoplasmic system that interprets the DNA into genes and creates intracellular and cellular networks to generation the observable phenotype. Even ecological factors such as diet and stress may modify the DNA such that different phenotypes can be constructed from the same DNA. During the past two decades, the basic principles of development have become known; although this brief chapter cannot do them justice (see, for example, Gilbert, 2013), they cover the following: mechanisms of differential gene expression; combinatorial logic of enhancers and promoters; signal-transduction pathways linking cell membrane and nucleus; mechanisms by which syndromes occur; the repertoire of morphogenetic interactions and the molecules causing them; environmental agents of phenotype production
