Homozygous grk^ΔFRT flies are viable, but the females are completely sterile. The egg chambers and eggs produced by homozygous grk^ΔFRT flies exhibit severe anteroposterior and dorsoventral patterning defects. grk^ΔFRT oocytes display defective oocyte-nucleus migration. grk^ΔFRT mutant females lay very few eggs and those that are laid are completely ventralised, most readily evident by their elongated shape and absence of dorsal appendages on their eggshells. Such eggs are also translucent and extremely fragile. grk^ΔFRT females produce a high percentage (several ovariole) of compound egg chambers, i.e. egg chambers that contain two or more germ-line cysts encased in a single follicle cell epithelium.

grk^GLS.mut fails to rescue the female sterility of grk^ΔFRT mutants. The grk^GLS.mut transgene exhibits no or only weak rescue of the dorsoventral patterning defects of grk^ΔFRT flies. Approximately half of the recovered eggs are fully ventralised and similar to those produced by grk^ΔFRT females. The remaining recovered eggs are strongly ventralised, containing a single small appendage on the dorsal midline. The grk^GLS.mut transgene exhibit incomplete rescue of the anteroposterior patterning defects of grk^ΔFRT flies.Thus while nuclear migration is consistently delayed and sometimes incomplete, most stage 8 and older egg chambers contain a correctly positioned nucleus. grk^GLS.mut rescues the compound egg chamber phenotype of grk^ΔFRT.