Pathogenesis of chronic constipation in a Polish group of paediatric patients – an attempt to create the optimal histopathological diagnostic protocol - Sylwia Szymańska; Malgorzata Markiewicz-Kijewska; Michal Pyzlak; Agnieszka Wieckowska-Karkucinska; Piotr Kalicinski; Wiesława Grajkowska; Maciej Pronicki (Gastroenterology Review)