Sampling and preliminary analysis of the extra‐ and intracellular material involved in the attachment of human oral epithelium in vitro

To simulate the environmental relationships of the junctional epithelium of gingiva, epithelial cells (epibolus) from explants of human oral mucosa were let to grow between the connective tissue of the explant and an underlying non‐collagenous substrate (Millipore® filter) for 9 days. The epithelial cells in contact with the filter attained a basal cell‐like morphology and secreted electron dense material eventually resembling a morphological basement membrane onto the filter. Short epithelial projections and disconnected vesicular structures were seen within the filter pores. After the establishment of the epithelium‐substratum junction, the explants were detached with alkali treatment. The accumulated proteins associated with epithelial attachment were now left within the filter. The electrophoretic analysis of these extra‐ and intracellular “filter” proteins revealed about 20 distinguishable polypeptide bands. The immunoreactions of the protein blots allowed to identify 4–4 cytokeratins and laminin. No specific polypeptides were discovered with the anti‐type IV collagen antibodies. However, a minor, proline‐rich band of epithelial origin was identified in the fluorography. The described in vitro method provides a way of sampling of the components involved in the epithelial attachment for a further biochemical analysis.