Approximately 17% of eggs derived from homozygous females and 24% of eggs derived from tsu⁶/tsu⁷ females have a ventralised phenotype similar to that of eggs derived from hemizygous mago¹ females. More than 60% of eggs derived from homozygous or tsu⁶/tsu⁷ females are abnormal, having defective dorsal appendages which are fused and/or shorter than normal, but having normal aeropyles. None of the embryos hatch and approximately 60% of eggs derived from tsu⁶/tsu⁷ females appear to be unfertilised. The remaining embryos from these females develop to the cellular blastoderm stage, but primordial germ cells are not formed. Microtubule organisation appears to be abnormal in tsu⁶/tsu⁷ egg chambers. The oocyte nucleus is mislocalised in approximately 20% of stage 9 and 10 homozygous egg chambers.