1. Reproductive Sciences Program (S.N., D.L.F.), University of Michigan, Ann Arbor, Michigan 48109;
2. Departments of Medicine (Y.Z., C.A.J.), University of Michigan, Ann Arbor, Michigan 48109;
3. Department of Animal Sciences, University of Missouri (D.K.), Columbia, Missouri 65211
4. Departments of Obstetrics and Gynecology (D.L.F.), University of Michigan, Ann Arbor, Michigan 48109;
5. Departments of Biology (D.L.F.), University of Michigan, Ann Arbor, Michigan 48109;
6. Ann Arbor Veterans Affairs Medical Center (C.A.J.), Ann Arbor, Michigan 48105;