Homozygous larvae and adults do not have melanotic capsules.
In the presence of additional dl protein, the mild maternal haploinsufficiency becomes more severe and only 11% of embryos hatch. Females transheterozygous for a cact gain of function allele and a loss of function allele result in embryos in which ventral structures are progressively lost at the expense of dorsal structures as the strength of the loss of function allele increases.
Moderate ventralizing phenotype: dorsal epidermis is replaced by naked epidermis of more lateral positions and sense organs of the head are lost. Expansion of twi expression in terminal regions.
Eggs derived from homozygous females cellularise normally but become abnormal at gastrulation. The cephalic furrow is very deep on the dorsal side during gastrulation and in many cases the germband does not extend at all or moves only a short distance around the posterior pole onto the dorsal side of the egg. Consequently, the posterior midgut invagination forms close to the posterior pole. The dorsal folds do not form and no amnioserosa is apparent. 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.
Embryos derived from homozygous females are partially ventralised.