<prompt> Earliest pathological change is X-ray in UIcreative Colitis-Loss of haustrationAphthous ulcerattionsMucosal granularitySkip tensions  <response>: Pathogenesis of inflammatory bowel disease. Bacterial antigens are taken up by specialised M cells, pass between leaky epithelial cells or enter the lamina propria through ulcerated mucosa. After processing, they are presented to type 1 T-helper cells by antigen- presenting cells APCs in the lamina propria. T-cell activation and differentiation results in a Th1 T cell-mediated cytokine response with secretion of cytokines, including interferon gamma IFN-g. Fuher amplification of T cells perpetuates the inflammatory process with activation of non-immune cells and release of other impoant cytokines, Including interleukin 12 IL-12, IL-23, IL-1, IL-6 and tumour necrosis factor alpha TNF-a. These pathways occur in all normal individuals exposed to an inflammatory insult and this is self-limiting in healthy subjects. In genetically predisposed persons, dysregulation of innate immunity may trigger inflammatory bowel disease. Inflammation invariably involves the rectum proctitis and spreads proximally in a continuous manner to involve the entire colon in some cases pancolitis. In long-standing pancolitis, the bowel can become shoened and post-inflammatory pseudopolyps develop; these are normal or hyperophied residual mucosa within areas of atrophy . The inflammatory process is limited to the mucosa and spares the deeper layers of the bowel wall . Both acute and chronic inflammatory cells infiltrate the lamina propria and the crypts cryptitis. Crypt abscesses are typical. Goblet cells lose their mucus and, in long-standing cases, glands become distoed. Dysplasia, characterised by heaping of cells within crypts, nuclear atypia and increased mitotic rate, may herald the development of colon cancer. Histology of ulcerative colitis. There is surface ulceration and inflammation is confined to the mucosa with excess inflammatory cells in the lamina propria, loss of goblet cells, and crypt abscesses arrows. SM submucosa Ref Davidson edition23rd pg 816 