Onset of cell proliferation in the shortened gut. Colonic hyperplasia after ileal resection.

Cytokinetics in colonic mucosa were studied after ileal resection in young female rats. The RNA content of the transverse colon was increased 32% after 7 days; after 14 days the increase was present throughout the colon. The DNA content of the ascending colon increased 29% after 10 days. Specific activity of DNA labeled with [3H-methyl]thymidine was elevated 29% in the ascending colon and elevated 49% in the descending colon on the 7th postoperative day. Colonic cell proliferation is stimulated within 1 week of ileal resection.