Embryos derived from mutant females have anterior and posterior holes in the cuticle. Neuroblasts delaminate normally and enter mitosis shortly after delamination in mutant embryos. 86% of the asymmetric cell divisions in the mutant neuroblasts are oriented along the apical-basal axis (as occurs in wild type).

Maternal effect on gastrulation.

Eggs derived from homozygous females cellularise normally but become abnormal at gastrulation; the posterior midgut is missing and no advancement of the germband around the posterior pole is seen. Extensive folding of the germ band is seen along the ventral side of the egg. This phenotype resembles that of fog mutants. The anterior midgut appears to form normally. The cuticle has holes at the anterior and posterior ends and there are frequent defects in the head skeleton, although the thoracic and abdominal segments appear fairly normal.