The ovarioles of stwl²⁶²⁷⁰⁸/stwl²⁶²⁷⁰⁸ mutant adult females contain some abnormally developing egg chambers, and some ovarioles are devoid of egg chambers; spectrosomes are absent from mutant germaria, and branched fusomes are largely absent from the ovary, although an excess of fusomes with a low level of branching remain; and there is a dramatic reduction in stem cell number in mutant germaria over the first week of adulthood, and abnormal expansion and elongation of the germaria. A number of germaria in stwl²⁶²⁷⁰⁸/stwl²⁶²⁷⁰⁸ mutant pupae show defects including reduced germline stem cell number, lack of germline, or discontinuous production of cysts.