embryo develops through a se- tion (7,8), thus complementing the gradient of Bicoidries of rapid syncytial nuclear divisions. The nuclei mi- (Fig. 1a).grate to the egg membrane at the periphery to form The third maternal transcription factor is the zincindividualcells.Thisformationis achievedbythemem- finger protein Hunchback, which becomes asymmetri-brane extending between the nuclei to generate a sin- callydistributedinresponseto