1. Department of Pharmaceutical Technology, University of Regensburg, 93053 Regensburg, Germany.
2. Department of Human Anatomy and Embryology, University of Regensburg, 93053 Regensburg, Germany.
3. Department of Physiology, University of Regensburg, 93053 Regensburg, Germany.
4. Department of Ophthalmology, Munich University Hospital, Ludwig-Maximilians-University Munich, 80336 Munich, Germany.
5. Institute of Anatomy and Cell Biology, Julius-Maximilians-University of Wuerzburg, 97070 Wuerzburg, Germany.