ORIGIN AND SPECIFICATION OF TYPE-II SENSORY NEURONS IN DROSOPHILA

The peripheral nervous system (PNS) of Drosophila is a preferred model for studying the genetic basis of neurogenesis because its simple and stereotyped pattern makes it ideal for mutant analysis, Type I sensor y organs, the external (bristle-type) sensory organs (es) and the inte rnal (stretch-receptive) chordotonal organs (ch), have been postulated to derive from individual ectodermal precursor cells that undergo a s tereotyped pattern of cell division. Little is known about the origin and specification of type II sensory neurons, the multiple dendritic ( md) neurons. Using the flp/FRT recombinase system from yeast, we have determined that a subset of md neurons derives from es organ lineages, another subset derives from ch organ lineages and a third subset is u nrelated to sensory organs, We also provide evidence that the genes, n umb and cut, are both required for the proper differentiation of md ne urons.