Figure 22.7: Dorsal protein in the nuclei helps to determine the dorsal–ventral axis of the Drosophila embryo. (a) relative concentrations of Dorsal protein in the cytoplasm and nuclei of cells in the early Drosophila embryo. (b) Micrograph of a cross section of the embryo showing the Dorsal protein, darkly stained, in the nuclei along the ventral surface.
[Part b: Max Planck Institute for Developmental Biology.]