Dorsal-ventral polarity in the Drosophila embryo

Embryonic dorsal-ventral polarity in Drosophila is established through a series of successive steps and requires the functions of both maternal and zygotic genes. The graded distribution of the transcription factor dorsal in blastoderm nuclei represents the transition from the maternal to the zygotic program. This results in the activation of specific zygotic genes that act to create the regional pattern along this axis.