Department of Medical Chemistry, Kochi Medical School, Nankoku, Japan; 2Department of Biochemistry, School of Pharmacy, Tokyo University of Pharmacy and Life Science, Japan; 3Department of Anatomy and Cell Biology, Kochi Medical School, Nankoku, Japan We previously generated mice lacking aromatase activity by targeted disruption of Cyp19 (ArKO mice), and reported phenotypes of the female mice, showing hemorrhage formation and follicular depletion in the ovary, diminution in uterine size, and bone loss.