XX dsx^S/dsx⁴³ animals develop as pseudomales.

dsx¹/dsx⁴³ females have a pheromone profile that resembles, to a first approximation, that of wild-type males. Subtle effects on viability (6-8%) are seen at 25^oC and 29^oC in flies carrying dsx^F.Hsp83 in a dsx¹/dsx⁴³ background. At 18^o to 25^oC, the genitalia are incompletely feminised, although they are clearly more feminised than the intersexual genitalia of XX dsx¹/dsx⁴³ animals. The male genital arch, which is normally found in XX dsx¹/dsx⁴³ animals, is missing although the pigmentation of abdominal segments A6 and A7 is similar to that observed in XX dsx¹/dsx⁴³ animals. The flies have mature, overfilled ovaries containing multiple late-stage eggs. At 29^oC, pigmentation and external genitalia of females carrying dsx^F.Hsp83 in a dsx¹/dsx⁴³ background resembles that of wild-type females. 10-15% of the females are rescued to fertility by a single copy of dsx^F.Hsp83. The remaining females are sterile and do not lay eggs. The reason for this sterility is unclear; the external genitalia and internal structures of the gonad closely resemble wild-type and the ovaries are morphologically normal and filled with many late-stage eggs. XY flies carrying dsx^F.Hsp83 in a dsx¹/dsx⁴³ background are transformed into pseudofemales at 25^o or 29^oC. Externally, these pseudofemales have female abdominal pigmentation and female genitalia and lack sex combs. This external feminisation is fully penetrant with invariant expressivity. Internally, although a uterus is present and male-specific structures such as the accessory glands are absent, the germline and surrounding soma is underdeveloped; there are no distinct ovarioles or developing egg chambers - only amorphous germline/soma cell clusters are seen. There is a complete loss of sex combs (they are transformed into female bristles). Viability is reduced by 38-40% compared to dsx¹/dsx⁴³ males. These pseudofemales show little interest in females and perform only early mating behaviours (orientation, tapping, wing extension and vibration). They actively reject courting wild-type males, but do allow themselves to be mated. Unlike wild-type females they continue to move around the chamber during copulation and flick their wings in an apparent attempt to dislodge the male.

Homozygous females have abnormal egg chambers, both their shape and the positioning of the follicle cells is abnormal.