FIGURE 1.

(A) Explant cultures and appearance of first cells growing out of the lip tissue (T) three to 6 days after initiation. Note how the cell colony is growing from day to day and the morphological differences between spindle-shaped fibroblasts (F) and the tightly packed, cobblestone-like keratinocytes (K) the dotted line represents the border between keratinocytes and fibroblasts. Scale bar: 250 μm. (B) Trypsinization of the cells 6 days after explant initiation often results in mixed cultures containing fibroblasts and keratinocytes. The morphological differences of the two cell types are visible in the brightfield pictures (top row) and when using phalloidin (red), which stains F-actin (second row, left two columns). Immunofluorescent stainings for a mesenchymal marker, Fibronectin (FN) and two epithelial proteins, Lamininγ2 (LAMC2) and E-Cadherin, respectively, confirms mesenchymal and epithelial origin of the cells. At the bottom, the merge of rows two and three including DAPI (blue) is shown. Note that keratinocytes secrete a large amount of LAMC2 that is deposited onto the culture dish while they move around. In contrast, FN is specifically detected where fibroblasts are located (e.g., see third column, rows two and three). Scale bar: 250 μm.