Intercellular junctions of oral epithelium: II. Ultrastructural changes in rat buccal epithelium induced by trypsin digestion

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The changes in structure of the plasmalemma and intercellular junctions of rat oral epithelium have been investigated by freeze-fracture and lanthanum impregnation after in vitro treatment of mucosal strips with trypsin. In all layers the density of intramembrane particles was reduced in the extrajunctional portions of the plasmalemma. The intercellular components of the desmosomes were severely altered, as shown first by the disappearance of the dense internal material and then by the rupture of the filaments connecting the plasmalemmas. The latter phenomenon led to the separation of adjacent cells. A detachment of the basal cells from the basal lamina with a modification of the structure of hemidesmosomes was also observed. Trypsin treatment induced a large increase of the fractional area occupied by gap junctions in the plasmalemma. The fine structure of this type of junction, as well as the size and shape of the intramembrane particles, remained unchanged. Also tight junctions were increased, both in the spinous and granulosum as well as between the corneum and granulosum strata. These junctions appeared as single strands and small maculae occludentes devoid of complex organization. These findings support the idea that desmosomes are complex structures composed of cytoplasmic, membranous and extracellular components. When the latter were affected the former appeared unchanged and maintained their position with respect to the plasmalemma. On the contrary, gap and tight junctions are plastic structures, whose assembly and disassembly is probably regulated by a number of factors, including the protein organization of the plasmalemma.

References (19)

  • AlbertiniD.F. et al.

    Tissue Cell

    (1975)
  • FukuyamaK. et al.

    J. Ultrastruct. Res.

    (1974)
  • GalliP. et al.

    Exp. Cell Res.

    (1976)
  • HaywardA.F. et al.

    J. Ultrastruct. Res.

    (1973)
  • ShimonoM. et al.

    J. Ultrastruct. Res.

    (1976)
  • StewartP.S. et al.

    J. Biol. Chem.

    (1974)
  • AmsterdamA. et al.

    J. Cell Biol.

    (1974)
  • BenedettiE.L. et al.
  • BorysenkoJ.Z. et al.

    Amer. J. Anat.

    (1973)
There are more references available in the full text version of this article.

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Present address: Department of Pathology, Tokyo Dental College, Chiyoda-ku, Tokyo-101, Japan.

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