Early intestinal microparticle uptake in the rat.

This time-course study investigates the early uptake and passage of microparticles across the intestinal mucosa. Single intraoral doses of fluorescent latex particles, 1.82 microns in diameter, were administered to young adult male, nonfasted rats at a dose of 1.88 x 10(9) particles. Peyer's patch regions and mesenteric lymph nodes were collected at 5, 15 and 30 min time points for both bulk tissue and morphological analyses. Particles were found at all experimental time points in macerated intestinal and nodal specimens: particle numbers were higher in proximal than in distal intestine at all time points despite the fact that particle numbers in distal Peyer's patch regions increased with time. Particle numbers in mesenteric lymph nodes also increased with time after administration. Detailed morphological data for several intestinal and nodal tissue compartments showed substantial early uptake of particles by villous epithelium, including goblet cells, but low involvement of follicle-associated cells. The distribution of particles in the lymph nodes confirmed that translocation occurred to all nodal compartments. These studies give confirmatory evidence that uptake and translocation of microparticles may take place as early as 5 min after administration and suggest that intestinal region may influence uptake.