On the Permeability of Oral Mucous Membrane for a Lipoid Unsoluble Acid Dyestuff, Trypan Blue

Abstract

The experiment was carried out by dropping solutions of trypan blue, a lipoid unsoluble acid dyestuff, on the oral mucous membrane of mice and observing how it invades into the subepithelial tissue.1. The first experiment was carried out by dropping for 1 hour the 0.5% dye soiutiln, resulting in staining only the upper layer of the epithelium. The second test was tried by dropping for 1 hour the solution containg 0.5% hydrochloric acid or half saturated with bicarbonate of soda, causing the staing of the subepithelial connective tissue, whereas the half an hour's dropping of the solution containing 10% of the hyaluronidase-preparation demonstrated the same result as the second test showed.In case of deep staining connective tissues, almost all tissue elementes such as connective tissue fibres, fibrocytes, walls of cappilaries and muscular fibres are stained evenly. The dye which staines the walls of the blood vessels also seems to run into the blood stream.2. The hydrochloric acid which was added to the the dye solution injured the epithelium, the added bicarbonate of soda and hyaluronidase caused a reduction of the viscosity of mucus, and made the diffusion of the dyestuff easier.3. The walls of the ducts of oral glands are relatively more easily passed by trypan blue. This indicates these parts to be a locus minoris resistentiae for the invasion of virus, bacilli etc.4. The oral mucous membrane of mice, so far as it is normal and intact will never permit the passing of lipoid unosluble molecules and particles of 2-5mμ diameter. Therefore in its normal state, no virus can presumably pass it, but provided the mucus covering is removed or resolved, a danger of virus passing it is increases.