The microvillus in adult jejunal mucosa--an electron microscopic study.

The increase in surface area contributed by microvilli per square unit mucosal surface area in the jejunal villus, i.e. amplification factor, has been studied in four normal adults and three adults with treated coeliac disease. Villi were split into three regions, photomicrographs of microvilli were taken from each region and the microvillus amplification factor calculated. The mid-villus region contributed a significantly greater microvillus amplification factor than either the low or upper regions in all patients studied. In addition surface cell heights were greatest in the low- and mid-villus regions. This suggests that the enterocytes in the mid-villus region are best adapted for absorption, and that the enterocytes in the upper-villus regions are undergoing an ageing process.