1. Center for Regenerative Biology, University of Connecticut, Storrs, Connecticut.
2. Present address: Reproductive Biology Associates, Atlanta, Georgia.
3. Present address: National Institute of Biological Sciences, Beijing, P.R. China.
4. Institute of Biotechnology, National Taiwan University, Taipei, Taiwan, Republic of China.
5. Reproductive Biology Associates, Atlanta, Georgia.
6. Department of Animal Science, University of Connecticut, Storrs, Connecticut.
7. Department of Molecular and Cell Biology, University of Connecticut, Storrs, Connecticut.