Membrane coating granules: The fate of the discharged lamellae

Rat gingival epithelium was found to be a favorable tissue for studying the fate of the contents of membrane-coating granules. Prior to horny cell formation the lamellar contents of these granules are discharged into the intercellular spaces between uppermost granular cells and between granular and horny cells. After discharge the lamellae coalesce, mix with existing intercellular material, and form broad sheets in the intercellular spaces. In the mid and upper regions of the stratum corneum, membranelike figures or bilayers of indeterminant length are seen in the intercellular spaces. These membranes are oriented parallel to, and often are in contact with, the horny cell membrane; thus, they may act as a barrier against penetration of substances into the skin. This investigation was supported by Research Grant No. AM 14693, National Institute of Arthritis and Metabolic Diseases, United States Public Health Service.