The cytoskeleton of the early Drosophila embryo.

The organization and roles of the cytoskeleton are described for a complex developing system (the early Drosophila embryo) at a time when the basic embryonic plan is mapped out. This type of embryo shows a separation of mitosis from cytokinesis during the early stages of development. Most cells are only formed when a syncytium of approximately 6000 nuclei are present. The functions of the cytoskeleton are considered for the process of nuclear migration (pre-blastoderm), which distributes the nuclei throughout the embryo and brings most of them close to the surface. They are also described for the subsequent mitoses of the syncytial blastoderm where the cortex and its well-developed cytoskeleton is reorganized into cell-like surface protrusions known as 'caps' or 'buds'. A comparison is made of the very different cytoskeletal organization present during the cleavages that form the two cell types of early development (pole cell and blastoderm cell), together with information from mutations that affect various aspects of these cleavages via factors laid down during oogenesis.