stet⁸⁷¹ mutant clones contain normal number of adult midgut progenitor cell clusters.

The early germ cells fail to differentiate and instead accumulate in third larval instar stet⁸⁷¹/Df(3L)PX62 testes. Many of these larval early germ cells remain mitotically active. Somatic hub cells are present at the apical tips of third instar mutant testes, but the hub often appears slightly enlarged and less tightly packed than normal. The somatic cyst cells do not appear to envelop germ cells in the mutant testes, and appear round, with 10-30% having detectable short cytoplasmic extensions. Adult stet⁸⁷¹/Df(3L)PX62 males have tiny testes filled with small cells that resemble the cells normally found only at the tip in the wild-type testis. The mutant testes appear to contain a mixture of germ cells with stem cell, gonialblast and spermatogonial identities. The egg chambers of stet⁸⁷¹/Df(3L)PX62 females often contain abnormal numbers and arrangements of germ cells. In older females, 90% of ovarioles usually have only a few egg chambers, which often show signs of degeneration. By 2 weeks after hatching, all ovarioles are mostly empty, except for the germaria, which contain increased numbers of early germ cells. The inner sheath cells do not form normal numbers of cytoplasmic extensions.