Developmental biology seeks to understand the array of processes by which a fertilized egg gives rise to the diverse tissues of the adult body. Examples of several developmental processes have been annotated here. In the early embryo, transcriptional regulation of pluripotent stem cells, gastrulation (including NODAL signaling), and activation of HOX genes during differentiation are annotated. Annotations of later, more specialized processes include nervous system development, cardiogenesis, aspects of the roles of cell adhesion molecules in axonal guidance and myogenesis, transcriptional regulation in pancreatic beta cells, adipogenesis, transcriptional regulation of granulopoeisis, transcriptional regulation of testis differentiation, LGI-ADAM interactions, and keratinization.

Transitions between cell types and cell states in developmental and differentiation processes are annotated as developmental cell lineages.