Influence of Drosophila ventral epidermal development by the CNS midline cells and spitz class genes.

The ventral epidermis of Drosophila melanogaster is derived from longitudinal rows of ectodermal precursor cells that divide and expand to form the ventral embryonic surface. The spitz class genes are required for the proper formation of the larval ventral cuticle. Using a group of enhancer trap lines that stain subsets of epidermal cells, it is shown here that spitz class gene function is necessary for ventral epidermal development and gene expression. Analysis of single-minded mutant embryos implies that ventral epidermal cell fate is influenced by the CNS midline cells.