1. Department of Anatomy and Embryology, Leiden University Medical Center, Leiden, the Netherlands (G.C., L.M.W., B.J.v.M., M.B., C.L.M.).
2. MESA+ Institute (B.J.v.M.), University of Twente, Enschede, the Netherlands.
3. Department of Biology, University of Padua, Italy (M.B.).
4. Veneto Institute of Molecular Medicine, Padua, Padua, Italy (M.B.).
5. Department of Applied Stem Cell Technologies (C.L.M.), University of Twente, Enschede, the Netherlands.