Eggs derived from homozygous females initiate development and cytoplasmic clearing occurs in a narrow zone around the egg periphery (in wild-type embryos this process is coupled to the arrival of the nuclei at the periphery). 80% of the eggs do not seem to develop beyond this stage; pole cells are not formed and cellularisation does not occur. However, about two hours after cytoplasmic clearing, the egg periphery starts to show local contractions, in what might be an attempt at gastrulation. These contractions eventually lead to eggs which typically have one or two condensed yolk balls surrounded by more transparent cytoplasm. 20% of the eggs show variable cellularisation.