ABSTRACT
SUMMARY The cleavage divisions in the early Drosophila embryo take place in the absence of cytokinesis, thus forming a large multinuclear cell. The transition from this syncycial stage to the first epithelium, the blastoderm, is achieved by the gradual ingrowth of the egg’s plasma membrane. Later, those parts of this epithelium, which contribute to the ectodermal epithelia, undergo extensive morphogenetic movements necessary for the elaboration of the final body plan. This chapter will summarise our current knowledge on the mechanisms and molecules controlling the establishment and maintenance of epithelial cell polarity. Surprisingly, despite the enormous differences in the generation of the blastoderm stage between vertebrates and Drosophila, some of the mechanisms required for the establishment and maintenance of epithelial cell polarity appear to be conserved and make use of the same molecules during the development of the respective epithelia. This chapter summarises aspects of Drosophila epithelial development and points out at novel mechanisms, for which no counterparts have been identified in vertebrates so far. The molecular and functional analysis of these mechanisms in Drosophila will contribute to our understanding of the genetic and molecular basis of the development of epithelial cell polarity, and will certainly have important implications for the development of epithelia in general.
