Partial hyperploidy of the X-chromosome inDrosophila hydeileading to duplication of male gonadal and genital structures

Introduction of two doses of the X-chromosomalwmCo duplication next to a normal X-chromosome in males ofD. hydeileads to duplication of testis tissue and structures derived from the male genital disc. The effect of this partial hyperploidy of the X-chromosome seems restricted to the male. We tentatively conclude that this part of the X-chromosome contains some factor(s) which may specifically affect the reproductive system and analia of males.