1. Department of Anatomy and Cell Biology (G.C., L.M.C., M.N.L.), The University of Western Ontario, London, Ontario, Canada N6A 5C1
2. Departments of Pediatrics, Obstetrics and Gynecology, and Molecular and Integrative Physiology (V.P.), University of Michigan, Ann Arbor, Michigan 48109
3. Department of Physiology and Pharmacology (R.L.G.), West Virginia University, Morgantown, West Virginia 26506