Genetic mechanisms of early neurogenesis in Drosophila melanogaster.

The neurogenic ectoderm of Drosophila melanogaster consists of the ventral neuroectoderm and the procephalic neuroectoderm. It is hypothesized that epidermal and central neural progenitor cells separate from each other in three steps: conference on the neuroectodermal cells the capability of producing neural or epidermal progenies, separation of the two classes of progenitor cells, and specification of particular types of neuroblasts and epidermoblasts. Separation of neuroblasts and epidermoblasts is controlled by proneural and neurogenic genes. Delta and Notch serve as mediators of direct protein-protein interactions. E(SPL)-C inhibits neurogenesis, creating epidermal cells. The achaete-scute complex (AS-C) controls the commitment of nonoverlapping populations of neuroblasts and leads the development of neuroectodermal cells as neuroblasts.