Correction

Some spelling errors were discovered following the publication of this work [1]. The correct spelling of one of authors name is Dr. Dieter Swandulla and not Dr. Dieter Schwandulla. Accordingly his correct e-mail address is Dieter.Swandulla@ukb.uni-bonn.de. The correct spelling of the University of Bonn is Rheinische Friedrich-Wilhelms-University of Bonn. In addition the current address of Dr. Carsten Theiss is Institute of Anatomy, Department of Cytology, Medical Faculty, Ruhr University of Bochum, Bochum, Germany. We apologise for any inconvenience this may have caused.