[Vesicular peroxidase transport by the epithelial cells of the small intestine in the adult rat].

Electron cytochemistry has shown that after administering horse radish peroxidase to the gastrointestinal tract of adult rats it penetrates the epithelial barrier of the small intestine and is transported functionally intact into the circulation. Peroxidase was largely absorbed on the apex of the villi, entered the enterocytes by pinocytosis and was transported via the cytoplasm within the pinocytotic vesicles. Peroxidase was not detected in cytosole or endoplasmic reticulum of the enterocytes. It is assumed that the disclosed functional heterogeneity of absorption depends on adsorption selectivity of the microvilli of the enterocyte apical membrane. It is concluded that the pinocytotic mechanism also functions in adult mammals, by which foreign protein is transported to the circulation, causing allergic reactions.