dib^P3/dib^F8 embryos have no denticle belts, dorsal hairs or differentiated mouth parts. Only a thin cuticular remnant containing both dorsal and anterior holes is secreted by most embryos. dib^P3/dib^F8 embryos appear to develop normally to approximately stage 14. At this point, many morphogenetic movements including dorsal closure, head involution, midgut morphogenesis and hindgut looping become abnormal. Midgut cells form the bilateral vessel but often fail to migrate to enclose the gut and the normal constrictions are either not formed or form abnormally. The failure of the midgut to enclose the yolk leads to yolk granules being distributed throughout the embryo, and they often extrude through the dorsal opening. During this time, the epidermis begins to contract along the anteroposterior axis leaving the thoracic and abdominal segments in a highly compacted state (possibly because head segments fail to involute properly). The hindgut becomes more extended than normal or may show unusual coiling. Many embryos never complete dorsal closure and when development terminates, the embryos are highly contracted with non-involuted head segments protruding anteriorly and gut and yolk protruding posteriorly. The amount of cell death appears to be normal during these abnormal late stages of embryogenesis. dib^P3/dib^F8 embryos derived from females with homozygous dib^F8 germline clones (lacking both maternal and zygotic dib function) show the same range and timing of defects as dib^P3/dib^F8 embryos (lacking zygotic dib function), suggesting that dib is not required in the germline during oogenesis or during early embryogenesis before stage 14. A low level (less than 1%) of escapers is seen in dib^F8/dib^13A animals. These flies appear normal and are fertile. 7 to 12 hour homozygous embryos contain very low concentrations of both ecdysone and 20-hydroxyecdysone compared to control embryos.