Abstract
Systematic genetic analysis of the segmentation process in Drosophila has established a paradigm for the molecular control of the formation of metameric segments. However, it bas been suggested that some of the mechanisms involved ill this process ill Drosophila are uniquely adapted to the syncytial mode of embryogenesis is such higher dipterans. A particularly contentious problem is the role of early segmentation genes in short-germ insects, in which development proceeds by sequential addition of segments in a cellular environment. However, analysis of the expression of presumptive homologs of segmentation genes in holometabolous short-germ insects suggests that they do indeed have a role in segmentation and that the Drosophila paradigm may be more widely applicable than is usually assumed Most interestingly,, these results suggest that tbe molecular mechanisms of pattern formation ill noncellular and ill cellular environments may riot be as radically different as it is often thought to be.
