[Principles of particle resorption in the gastrointestinal tract]

The uptake of allergens by the epithelium of gastrointestinal tract is not sufficiently investigated. This is true especially for the absorption of small particles like spores and pollen. By means of scanning-electron-microscopy it is possible to locate particles easily and to observe absorption solutions of 0.5 micron and 1 micron latex particles, of 15 microns Urtica pollens and of 35 microns Lycopodium spores and further on by cannulation of the thoracic duct the transport of particles was investigated. After a short time of absorption latex particles were found to be concentrated on M-cells of Peyer's patches (PP) and were found in a close contact to macrophages inside the lymph follicles. There was a constant proportion of M-cells to absorptive-like cells in PP from about 1 to 12. Obviously all particles were also transported by thoracic duct lymph. The results obviously indicate: primary absorption of small particles occurs in M-cells of PP; absorption time is dependent on particle size and transport of particles is achieved by abdominal lymph.