1. Division of Cell Biology
2. Department of Forensic Medicine
3. Department of General and Clinical Pathology Medical University Varna, Bulgaria 9002
4. Institute of Neurobiology and Molecular Medicine National Research Council-European Brain Research Institute Rita Levi-Montalcini Rome, Italy 00185
5. Department of Embryology and Histology Medical Faculty Niš, Serbia
6. Department of Cardiovascular Surgery
7. Department of Internal Medicine University Hospital St Marina Varna, Bulgaria 9002