1. Specto Srl, Via Caradosso 12, 20123 Milan, Italy
2. Division of Anatomy, Center for Anatomy and Cell Biology, Medical University of Vienna, Waehringerstrasse 13, Vienna A-1090, Austria
3. Dipartimento di Fisica, Politecnico di Milano, Piazza L. da Vinci 32, 20133 Milan, Italy