Embryos derived from homozygous germline clones develop defects at gastrulation; the cephalic furrow is not visible, the ventral furrow is abnormal and germband extension is incomplete. Invagination of the anterior and posterior midgut occurs apparently normally.

Cells of the mesoderm anlage constrict on their apical side (as in wild type) in embryos derived from homozygous germline clones, but constriction is less coordinated than normal, and is incomplete after 10 minutes (all ventral cells constrict within this time in wild-type controls). The width of the stripe of constricting cells (14-18 cells) in the mutant embryos suggests that all mesodermal cells participate in apical constriction in the mutant embryos, in contrast to the 10-12 cell stripe of constricting cells seen in wild-type embryos. No proper ventral furrow is formed and the mesoderm anlage invaginates only partially or not at all.

The germband does not extend much beyond the posterior pole in embryos derived from homozygous germline clones. This is due to impaired cell intercalation within the lateral epidermis.