1. Center for Biotechnology, Department of Biosciences at NOVUM, Karolinska Institutet, S-14157 Huddinge, Sweden
2. Departments of Pathology and Anatomical Sciences, University of Missouri-Columbia, Columbia, MO 65211-5300, U.S.A.
3. Departments of Animal Sciences and Obstetrics & Gynecology, University of Missouri-Columbia, Columbia, MO 65211-5300, U.S.A.
4. Department of Anatomy and Cell Biology, Queen'sUniversity, Kingston, Ontario K7L 3N6, Canada