THE EPITHELIUM-TOOTH INTERFACE - A BASAL LAMINA RICH IN LAMININ-5 ANDLACKING OTHER KNOWN LAMININ ISOFORMS

The attachment of the marginal gingiva to the tooth surface is mediate d by a thin nonkeratinized epithelium termed the junctional epithelium (JE). Ultrastructural studies have revealed that the attachment of th e JE to the tooth surface occurs through hemidesmosomes (HD) and a bas al lamina-like extracellular matrix termed the internal basal lamina ( IBL). We have previously shown that neither type IV collagen nor proto typic laminin, two common components of basement membranes (BM), is pr esent in the IBL between the epithelium and the tooth. In the present study, we show that laminin-5 is a major component of the IBL in both rodent and human tissues. By using in situ hybridization, we also show that the cells of the JE express the LAMC2 gene of laminin-5. In othe r parts of gingival epithelium, LAMC2 gene expression is less prominen t. Our results indicate that the epithelium-tooth interface is a uniqu e structure wherein epithelial cells are induced to secrete a basal la mina containing laminin-5 and no other presently known laminin isoform .