CELL LINEAGE AND CELL FATE SPECIFICATION IN THE EMBRYONIC CNS OF DROSOPHILA

The Drosophila CNS derives from a population of neural stem cells, cal led neuroblasts (NBs), which delaminate individually from the neurogen ic region of the ectoderm. In the embryonic ventral nerve cord each NE can be uniquely identified and gives rise to a specific lineage consi sting of neurons and/or glial cells. This 'NB identity' is dependent o n the position of the progenitor cells in the neuroectoderm before del amination. The positional information is provided by the products of s egment polarity and dorsoventral (D/V) patterning genes. Subsequently, 'cell fate genes' like huckebein (hkb) and eagle (eg) contribute to t he generation of specific NB lineages. These genes act downstream of s egment polarity and D/V patterning genes and regulate different proces ses such as the generation of glial cells and the determination of ser otonergic neurons.