Spatial visualization of junctional complexes by backscattered electron imaging and silver staining

A method for the observation of junctional complexes by backscattered electron imaging in scanning electron microscopy, in tissue blocks, is presented. The junctional complexes are revealed by a modified silver staining method (originally devised for nucleolar organizer regions), used "en bloc" after formalin or glutaraldehyde fixation. Backscattered electron imaging allows, after this staining, the observation of junctional complexes through the surface of intact superficial cells, in the three tissues studied (liver, jejunum and urinary bladder). The interest of this approach is to offer the possibility of observing junctional complexes "by transparence," in nondissociated and nonsectioned tissues.