Sex reversal in C57BL/6J-YPOSmice corrected by aSrytransgene

Abstract

C57BL/6J mice carrying aMus domesticus poschiavinusY chromosome (Y^POS) develop as females with ovarian tissue or as hermaphrodites with ovarian and testicular tissue. We tested the hypothesis that the Y-linked component of this inherited sex reversal is caused by theM. d. poschiavinusY-linked testis determining gene (symbolizedTdyorSry) by examining gonadal development in C57BL/6J XY^POSmice carrying aM. musculusallele ofSryas a transgene. We found that in the presence of the transgene, XY^POSmice developed exclusively testicular tissue. This result indicates that theSryallele carried on the Y^PDSchromosome is responsible for development of ovarian tissue in the G57BL/6J inbred strain background. We discuss this finding in light of DNA polymorphisms present inSryalleles carried by variousM. domesticusandM.musculusY chromosomes. In addition, we present a hypothesis concerning the timing of expression of the testicular and ovarian determining genes in the developing fetal gonad based on the organization of ovarian and testicular tissue in ovotestes.