The striped pattern leads to the segmental array of segment polarity gene transcription. Here is a developmental hierarchy, each chain in the link of events made possible by what has preceded it, and making possible what has yet to come. It takes about two hours, beginning 11 hours after the start of development. Dorsal closure is the process whereby the stretched amnioserosa is covered by epidermal cells that will ultimately fuse at the dorsal midline. With its part in development played, the amnioserosa is then absorbed by the yolk.
Genes involved in dorsal closure include rho, hemipterous and basket .
The most rapid period of head involution occurs at the same time as dorsal closure. In the process of head involution, the anterior ectoderm moves to the interior, beginning with stomodeal invagination. Beginning at 6 hours into development, the process will take another 5 hours. The embryonic development of Drosophila melanogaster . Maternal and zygotic control of serotonin biosynthesis are both necessary for Drosophila germband extension.