Absorption of horseradish peroxidase by neonatal pig intestinal epithelium: effect of Escherichia coli (055B5) on absorption.

The pathway of macromolecular transport through the neonatal pig small intestinal epithelium was examined, utilizing the cytochemical marker horseradish peroxidase (HRP). The marker was found adsorbed to the apical microvillous of the enterocytes, within apical tubules, and cytoplasmic vacuoles. Extracellular absorbed marker assumed a spherical appearance within the subepithelial spaces but was dispersed within the capillary lumens. Uptake of HRP into the enterocyte occurred in 48-hour old neonatal pigs, but transport into the circulation was not observed. Adherence of Escherichia coli to the surface of the ileal enterocyte did not totally inhibit HRP uptake. The E coli adhered to the surface of the enterocyte or within intercellular vacuoles appeared to be static in as much as they were not involved in the transepithelial migration of envacuolated HRP.