Histology of colonic mucosa. (1a) Section of mucosa was stripped off the colectomy specimen and processed by formalin fixation and paraffin embedding. The mucosa is composed of the lamina propria and epithelium. As is evident, it is not a homogeneous collection of cells, but rather a composite of the cells that are present in the lamina propria (chronic inflammatory cells, smooth muscle cells and vessels) and epithelium (hematoxylin and eosin 10×). (1b) Histologic evidence of enrichment for colonic epithelial cells from the procurement approach described in the text (hematoxylin and eosin 20×).