1 Institute of Anatomy and Cell Biology, Saarland University, Campus Homburg, Kirrberger Str. 100, 66421 Homburg/Saar, Germany.
2 Institute for Clinical and Functional Anatomy, Medical University of Innsbruck, Müllerstrasse 59, 6020 Innsbruck, Austria. Electronic address: Erich.Brenner@i-med.ac.at.