Embryos deficient for both maternal and zygotic Btk29A function display no additional defects beyond the zygotic head involution defect. Only 40% of eggs laid by females with homozygous germ line clones are of normal size, the rest are smaller than normal. The reduction in size is variable, ranging from 50% to 100% of normal egg length. Approximately 70-80% of stage 14 oocytes are smaller than wild-type in females with homozygous germ line clones. Approximately 1/4 of these oocytes still have their nurse cells attached.