Growth and formation of 2D enteroids. 2D enteroid grown on Matrigel-coated cell culture plastic. A Bright field image of epithelial cells forming islands on day 1 of culture. B Fibroblast-like cells seen around the edge of the epithelial cell islands (arrows). C A confluent polygonal epithelial cell layer on day 3 and on D day 6 of cell culture. E Higher magnification of 2D enteroid on day 6 of culture. F Bright field image of 2D enteroid grown on an uncoated cell culture plastic. Representative images of 5–6 independent experiments. Scale bars: 100 µm.