A COMMON PRECURSOR FOR GLIA AND NEURONS IN THE EMBRYONIC CNS OF DROSOPHILA GIVES RISE TO SEGMENT-SPECIFIC LINEAGE VARIANTS

The nervous system consists of two classes of cells, neurons and glia, which differ in morphology and function. They derive from precursors located in the neurogenic region of the ectoderm. In this study, we pr esent the complete embryonic lineage of a neuroectodermal precursor in Drosophila that gives rise to neurons as well as glia in the abdomina l CNS. This lineage is conserved among different Drosophila species. W e show that neuronal and glial cell types in this clone derive from on e segregating precursor, previously described as NB1-1. Thus, in addit ion to neuroblasts and glioblasts, there exists a third class of CNS p recursors in Drosophila, which we call neuroglioblasts. We further sho w that the NB 1-1 lineage exhibits characteristic segment-specific dif ferences on the cellular level.