Is there circadian variation in villus height in rat small intestine?

Measurements of villus height, crypt depth and mucosal thickness were made for each of duodenum, jejunum and ileum of rat small intestine from animals on both unrestricted and restricted feeding regimens. Contrary to a previous report, there was no evidence for consistent or synchronized diurnal variation in villus height at any region of small intestine on any of the feeding regimes. Likewise, no diurnal variation was seen in crypt depth or mucosal thickness. Variation in villus cell numbers, therefore, cannot account for previously reported diurnal variation in absorptive and digestive activities in rat small intestine. The present results support the hypothesis that the stimulus for exfoliation is probably cell recruitment and migration up the villi.