Malpighian tubules of larvae are bloated and show a dramatic reduction in fluorescent concretions. Number of nuclei is similar to that of wild type and the epithelium is still formed by a monolayer showing an apicobasal polarity, but the apical side of the epithelial cells is highly abnormal. Extensive folds protrude into the lumen. The folded membrane is still associated with an apical cytocortex. Females with germ line clones show strongly reduced fertility. Affected embryos first show a defect as a delay in the formation of pole cells and a frequent reduction in number of pole cells. As nuclei reach the periphery, few actin filaments are present and no organisation into F-actin caps or mitotic pseudo-cleavage furrows can be detected. The spacing between nuclei becomes irregular. Many nuclei have abnormal shape, fuse and drop into the interior of the embryo. Cellularisation completely fails. The embryo remains a polynucleate mass, which gradually deteriorates.