Fig. 6. Eda-A1 overexpression caused enlargement of the first molar placode at E12 and an extra molar placode in E13 lower jaws. (A-F) Top views of lower jaws. The odontogenic molar (red arrows in A and B) and incisor (blue arrows in A and B) fields were visualised in E11 embryonic lower jaws by Pitx2 expression. No difference was seen between wild-type (A) and K14-Eda-A1 transgenic (B) embryos. At E12, the dental placodes were visualised by Shh expression (C,D). The molar placodes were larger in transgenic embryos when compared with controls (arrows in C,D). At E13, extra placodes (blue arrow) were located in front of the transgenic molar placodes (red arrow in F). However, a small Shh-positive placode was also detected in wild-type embryos (blue arrow in E). The size measurements of E12 mandibular molar placodes of K14-Eda-A1 and control mice are presented as a box plot presentation (G). The size measure is a product of width and length of a placode. The height of the box presents 50% of the results. Mean is shown as a horizontal line inside the box and 95% confidence limits are shown by the lines outside the box. The difference between groups is statistically significant (P=0.03) according to the Mann-Whitney U-test. Measurements were made on three litters of mice. Number of placodes measured: K14-Eda-A1 n=23; wild-type littermates, n=18. Scale bars: 1 mm.