Etude histologique de l'appareil genital du mutant d'intesexualite double sex ( DSX) de Drosophila melanogaster meigen (Diptere: Drosophilidae)

Abstract

If homozygous dsx dsx males and homozygous dsx dsx females of Drosophila melanogaster are turned phenotypically into intersexes, the structure of their sexual organs is also altered. In this paper, dsx dsx males are called XY intereexes, and dsx dsx females are called XX intersexes. Except 13.5% of XX intersexes, whose gonads are true ovaries, all other intersexes posess small and ovoid gonads. There are testes, ovaries or “diffused” gonads in XX intersexes, and testes or “diffused” gonads in XY intersexes. In the testes, the germ cells develop into primary spermatocytes (XY intersexes), remain as gonia (XX intersexes), or develop according to a female orientation (nurse cells, XX intersexes); agametic testes are also described. The ovaries are organized into ovarioles or not; the germ cells are only gonia, or nurse cells and possibly oocytes enclosed in follicles. In XY intersexes, the “diffused” gonads are testes incompletely enveloped by an inner and an outer sheath and the germ cells are only gonia. In XX intersexes, the mesodermic tissue is localized between the adipocytes, without any surrounding sheath; the germ cells develop into nurse cells enclosed in follicles, localized inside the mesodermic tissue, or remain as gonia, free in the body cavity. Some parts of the genital ducts cannot be identified as male or female ducts, the remaining organs being phenotypically male; however the “spermiducts” do not induce the coiling of testes. Even if dsx gene modifies homozygous males and homozygous females, the alterations are more important in homozygous females. As a matter of fact, development is altered in XY intersexes, but the orientation corresponds to the genetic sex (male); in XX intersexes, organs may develop according to a male orientation.