Figure 1. Examples of ALDH1A1 stem-like cell marker expression by immunohistochemistry in control colorectal mucosa and in baseline adenomas in relation to metachronous adenoma development (“recurrence”).
In non-neoplastic mucosa, the epithelial stem-like cells (arrows) are located near the bases of crypts (Panel A, with higher magnification in Panel B). In contrast, the stem-like cells in adenomas (Panels C through F) are distributed throughout the neoplastic glands, with smaller numbers near the luminal surface than in the deeper glands. An advanced adenoma with low-grade dysplasia but size greater than 1 centimeter in a participant who developed a metachronous adenoma (Panels C and E) has numerous ALDH1A1-positive stem-like cells, in contrast to an advanced adenoma with low-grade dysplasia that has only scattered stem-like cells (arrows) in a participant who was adenoma-free at follow-up (Panels D and F).