Drosophila developmentDevelopmental BiologyAxis formationAxis formationDevelopmental biology studiesDrosophila developmentEarly embryoEmbryoEpitheliumGastrulationGene Control in DevelopmentGerm cellHomeotic transformationHydatidiform molesMorphogen gradientOrganogenesisSRYSexSex determinationStem cellDrosophila melanogasterDrosophila developmentSubpagesDrosophila Sex-Lethal (Sxl) proteinDrosophila axis formationDrosophila germ layer formationDrosophila maternal effect genesDrosophila terminal system