Studies on the genetics of tda-1 XY sex reversal in the mouse

When the Y chromosome of at least some populations of the house mouse of Western Europe and the Mediterranean, Mus musculus domesticus, is placed into the C57BL/6J (B6) inbred mouse genome, XY fetuses develop into hermaphrodites or females. It has been hypothesized that the testis-determining gene on the Y chromosome of M. m. domesticus (TdyDOM) interacts improperly with a putative B6/J recessive, testis-determining, autosomal gene (tda-1). The present study extended these earlier findings. The mating of B6 mice possessing the Y chromosome of M. m. domesticus (B6.YDom/Na; N6-N9) to females of the AKR, BALB/c, C3H/An, and C3H/He, but not SJL, strains resulted in aberrant testicular differentiation in day-14/15 F1 fetuses. The aberrant testes were characterized by a delay in testicular differentiation at the cranial and caudal poles of the gonad, i.e., the presence of a thin (or no) tunica albuginea and the presence of disorganized (or no) seminiferous tubules. Crossing B6.YDom male phenotypes with SJL females did not result in aberrant testicular differentiation, suggesting that the SJL strain possesses the dominant testis-determining, autosomal-1 allele, Tda-1. Studies using recombinant DNA probes specific for the murine Y chromosome have suggested that the SJL and AKR strains possess the M. m. domesticus Y chromosome. When Y chromosomes of the SJL and AKR strains were placed on the B6 background, aberrant testicular differentiation similar to tda-1 XY sex reversal occurred in only 1 out of 87 (1%) N4 day-14/15 fetuses possessing YSJL, but in 25 out of 45 (56%) N4 day-14/15 fetuses possessing YAKR.(ABSTRACT TRUNCATED AT 250 WORDS)