Figure 1: A, the colonic mucosa in a healthy individual or in a patient with quiescent UC is well vascularised for efficient absorption of water and nutrients from the gut. B, in patients with active UC, the mucosa may be inflamed together with ulcers, vascular patterns are lost, and absorption of water and nutrients can be impaired. C, mucosal biopsy showing vast numbers of myeloid leucocytes in the inflamed mucosa. This patient had failed to respond to optimal doses of conventional medications.