Histochemical distribution of enzymes in the small intestine of young milk-fed calves

The histochemical distribution of selected enzymes were examined in the small intestine of 5 about 3-week-old normal calves fed on whole cow’s milk. Alkaline phosphatase and β-D-galactosidase (= lactase) in the epithelial brush border, and non-specific esterase in the cytoplasm showed a strong reaction in the villi of the anterior small intestine and a marked decrease in the posterior regions. Aminopeptidase in the brush border of the villi showed a reverse distribution, with the strongest reaction in the posterior small intestine. Adenosine-triphosphate-splitting enzyme in the epithelial brush border, acid phosphatase and succinate dehydrogenase in the cytoplasm of the epithelial cells gave a relatively uniform reaction in the villi throughout the small intestine. A fluoride-resistant acid phosphatase was demonstrated in the brush border of the villi in the anterior small intestine. The distribution of enzymes demonstrated in this study was generally compatible with the known absorptive functions of the various parts of the small intestine.