1. Harvard School of Dental Medicine (C.C., P.V.H.), Boston Massachusetts 02215
2. Children's Hospital Boston (C.C., P.V.H.), Boston Massachusetts 02215
3. Beth Israel Deaconess Medical Center (C.C.), Boston Massachusetts 02215
4. University of Cincinnati (C.C., J.H.), Cincinnati, Ohio 45267
5. Department of Human Anatomy and Histology (C.C.), University of Bari, Medical School, 70126 Bari, Italy
6. University of Alabama (M.Z.), Birmingham, Alabama 35294
7. Molecular Research Center (M.Ry.), Cincinnati, Ohio 45212
8. Department of Neuroscience (M.Ri.), Tufts University, School of Medicine, Boston Massachusetts 02111