1. Department of Gastroenterology, Allergology and Pediatrics, Polish Mother’s Memorial Hospital-Research Institute, Lodz 93-338, Poland
2. Division of Anatomy, Department of Human Morphology and Embryology, Wroclaw Medical University, Wroclaw 50-367, Poland
3. Division of Histology and Embryology, Department of Human Morphology and Embryology, Wroclaw Medical University, Wroclaw 50-367, Poland
4. Department of Pathology, Polish Mother's Memorial Hospital-Research Institute, Lodz 93-338, Poland