dsx^M/+ genital discs are intersexual; both male and female genital primordia develop in these discs.

Intersex phenotype. Cells derived from the female genital disc can develop male genital structures.

XX dsx^M/+ flies do not show any male-specific courtship when paired with mature virgin females. 100% of XY dsx^M/+ flies show male-specific courtship when paired with mature virgin females.

Sex specific neuroblasts fail to undergo any postembryonic divisions in male or female larval nervous systems.

Chromosomal females (XX) mutant for dsx are transformed into "pseudomales". They are sterile even in the presence of a Y chromosome. The gonads form testes.

Only affects XX flies: the terminalia of XX heterozygous flies carry abnormal male and female elements, with the female genitalia anterior to the male genitalia. The male genitalia are well developed, but the penis apparatus is reduced, the hypandrium is mostly absent and many bristles are abnormal. The female vaginal plate is always present, but is reduced in size with abnormal bristles. There is often a mass of yellow, chitinised material between the vaginal plates, which is a secondary rudimentary penis apparatus. The anal plates have a sexually intermediate shape, and a bristle pattern which is a mosaic of male, female and intermediate bristles. The basitarsus of the foreleg carries a sex comb whose position and shape are intermediate between male and female. XX hemizygotes are sterile pseudomales.

dominant; affects XX only