Figure 3. KROX-26 mRNA expression in embryonic (A) and adult (B) human tissues. Tissue sections from 12-week-old human embryos were hybridized with a digoxigenin-labeled KROX-26 antisense (a, c, e, g, i, k) or sense (b, d, f, h, j, l) probe and counterstained with methyl green. Positive signals in blue or brown (arrows), indicating KROX-26 expression, are seen in the epithelial component of the developing tooth (a, c, e), tongue epithelium (g), tongue striated muscle (i), and osteoblasts of craniofacial bone (k). Bars indicate 250 µm (a-f) or 100 µm (g-l). Abbreviations: B, bone; E, epithelium; M, mesenchyme. A multiple-tissue Northern Blot on human adult tissues (B) indicates the existence of a single 2.4-kb KROX-26 mRNA transcript in multiple tissues at various levels, relative to ß-actin mRNA expression.