Effect of animal age on the uptake of large particulates across the epithelium of the rat small intestine.

A quantitative investigation into the transfer of latex polystyrene particles across the epithelium of the small intestine has been carried out using male weanling, adult and aged Sprague-Dawley rats. Orally administered polystyrene particles, 2 microns in diameter, were transferred from the lumen of the small intestine into the gut associated lymphoid tissues (Peyer's patches). No significant difference in the number of particles transported across the gut epithelium was detected between animals of different age groups. The concentration of particles detected in Peyer's patches excised from the proximal and distal regions of the small intestine of particle-treated animals did not differ significantly, except in aged rats. Particle concentration was significantly higher in Peyer's patch tissue than in adjacent Peyer's patch-free tissues of the small intestine in treated animals of all age groups. The assay method described here may be used for quantitative investigation of the transepithelial transport of large particulates.