Weak ventralized phenotype: slightly wider than normal denticle belt. There is some zen function and some differentiation of amnioserosa. Embryos are more strongly ventralized at 29oC than 18oC. Temperature sensitivity is largely restricted to the syncytial blastoderm stage.
Eggs derived from homozygous females cellularise normally but become abnormal at gastrulation. The embryos are ventralised. The ventral denticle belts are expanded laterally and dorsal cuticle elements such as Filzkorper and spiracles are missing. Most of the head structures are absent.