Ultrastructural study of rabbit buccal epithelial cells and intercellular junction by scanning and transmission electron microscopy.

We observed by scanning and transmission electron microscopy the ultrastructure on the upper and lower surfaces of buccal epithelial superficial layer cells and the arrangement of intercellular junction apparatuses. In the superficial layer cells of the rabbit buccal epithelium, microvillus-like processes were observed on the lower surface and microridges on the upper surface. The distal portion of the microvillus-like process on the lower cell surface formed a wedge-like structure. At the intermicroridge areas on the upper cell surface, wedge-like depressions were observed. These depressions were interdigitated with the wedge-like structures of the microvillus-like processes. From the observation of the serial ultrathin sections, most interdigitation sites have two demosomes per microvillus-like process (89.5%). The desmosomes were located in the distal portion of the microvillus-like processes (99.3%). The wedge-like structures of the microvillus-like processes and wedge-like depressions on the inter-microridge areas seem to increase the junctional surface and enhance cell cohesion against external forces from various directions.