Rapid insorption of small particles in the gut.

Little is known about the uptake of small particles by the epithelium of the gastrointestinal tract. In our study, we investigated the absorption and transport of synthetic and natural particles by means of scanning electron microscopy (SEM). In Wistar rats, closed loops of jejunum with intact mesenteric blood supply were established in ether anesthesia so that we might study the absorption of latex particles of different sizes. After variable absorption times, loops were removed and prepared for examination by microscopic techniques. The average surface of M-cells was 35 +/- 2 microns2, whereas the total number was dependent on follicle size. The proportion of M-cells to absorptive-like enterocytes on follicle epithelium was 1:12. Latex particles were found easily on the surface of M-cells, and for the most part they were surrounded by microfolds. In only 10 min from the time of application, latex beads were concentrated or even included within macrophages of the dome of lymph follicles. The results indicate that primary insorption of small particles occurs in M-cells of Peyer's patches, and time of insorption is dependent on particle size.