A method for quantifying particle absorption from the small intestine of the mouse.

We have developed a method for quantifying the absorption of model fluorescent latex particles from the mouse small intestine into Peyer's patches, mesenteric lymph nodes, and spleen. The procedure combines a simple and exhaustive particle recovery technique with a highly sensitive particle counting technique. Mice were orally gavaged with fluorescent polystyrene latex suspensions, and at various time points Peyer's patches, normal absorptive small intestinal tissue, mesenteric lymph nodes, and spleen were collected. The tissue samples were solubilized using an aqueous potassium hydroxide and surfactant solution and particles were counted using a flow cytometer. Using this method we were able to detect and quantify small numbers of particles, measure the course of uptake and clearance, and determine the tissue distribution of absorbed particles. Data generated using this technique indicate that particle absorption depends on the dose level, particle size, and fed state of the animals.