Localized Lanthanum Staining of the Intestinal Brush Border

The use of lanthanum salts has made possible the staining of extracellular regions which are not electron opaque when conventional methods of fixation and staining for electron microscopy are employed (3, 6, 10). The present work describes the staining of the intestinal epithelium by this means. Intercellular regions in the intestinal wall generally stain intensely, as has been described previously in other tissues (3. 10), but the free surface of the epithelium is distinctive in that the stain is taken up here in localized regions. It is the purpose of this report to describe the character of these regions and their fine structure as shown by enzymatic breakdown.