Early development in Drosophila. During oocyte development, maternal mRNAs and proteins are deposited in the oocyte by nurse cells and follicle cells. After fertilization, nuclear divisions occur in synchrony in the common cytoplasm (syncytium), and nuclei migrate to the periphery. Membrane invaginations surround the nuclei to create a monolayer of cells at the periphery; this is the cellular blastoderm stage. During the early nuclear divisions, several nuclei at the far posterior of the embryo become pole cells, which later become the germ-