Uptake and transfer of particulate matter from the peritoneal cavity of the rat.

1. Colloidal mercuric sulfide or thorium dioxide injected intraperitoneally passes into the cytoplasm of the mesothelium of the mesentery and of the diaphragm as early as 15 to 30 minutes after the injection. 2. Between 15 minutes and 12(1/2) hours the number of particles within the mesothelial cells increases as the time between injection and termination of the experiment is lengthened. 3. The particulate matter is usually localized in the cytoplasm within clear vacuoles or bodies having a relatively dense matrix. 4. A greater quantity of the absorbed material is commonly observed within the cytoplasm of the diaphragmatic than of the mesenteric mesothelium.