SEXUALLY DIMORPHIC STERILITY PHENOTYPES IN HOXA10-DEFICIENT MICE

THE Abdominal B (AbdB) genes constitute a distinct subfamily of homeob ox genes that exhibit posterior domains of expression(1,2), including the genital imaginal disc in Drosophila and the developing urogenital system in vertebrates(3,4). We have mutated the AbdB gene Hoxa10 in mi ce, We report here that homozygotes are fully viable and show an anter ior homeotic transformation of lumbar vertebrae. All male homozygotes manifest bilateral cryptorchidism resulting in severe defects in sperm atogenesis and increasing sterility with age. Female homozygotes ovula te normally, but about 80% are sterile because of death of embryos bet ween days 2.5 and 3.5 post coitum. This coincides spatially and tempor ally with expression of maternal Hoxa10 in distal oviductal and uterin e epithelium. These results indicate a role for AbdB Hox genes in male and female fertility and suggest that maternal Hoxa10 is required to regulate the expression of a factor that affects the viability of prei mplantation embryos.