1. Department of Histology and Embryology, Pomeranian Medical University, 70-111 Szczecin, Poland
2. Department of Physiology, Pomeranian Medical University, 70-111 Szczecin, Poland
3. Department of Gastroenterological Surgery and Transplantology, National Medical Institute, Ministry of Interior Affairs and Administration, Wołoska St. 137, 02-507 Warsaw, Poland