Abstract

The formation of segments in the Drosophila early embryo is understood in greater detail than any other complex developmental process. Now, by studying other types of insect embryo, we can hope to deduce something of the ancestral mechanism of segmentation and the ways in which it has been modified in evolution. The parasitic wasp, Copidosoma floridanum, is spectacularly atypical of insects in that the small egg cell divides extensively, with no initial syncytial phase, and forms eventually some 2000 embryos(1). This process raises intriguing questions about the control of embryonic polarity and segmentation.