Fig. 5. Catnb^ex3K14/+ hair placodes form throughout the skin in a random and dense pattern. (A-J) Detection of placodes by expression of Sostdc1 (A-D,G,J), Wnt10b (E,H) and Shh (F,I) in E14.5 control (A,C,E-G) and Catnb^ex3K14/+ (B,D,H-J) skin showed dramatic spreading of mutant hair placodes throughout the skin, even in regions that, in control embryos, still lacked placodes: dorsal paw skin (arrow in B); the immediate surroundings of eye, ear lobe and vibrissa pads (arrows in D); and dorsal midline and tail skin (arrows in B''). Mutant placodes were also observed in ventral paw skin (B'), which in adult wild-type mice remain largely hairless. (E-J) High magnifications of dorsal skin revealed the regularly spaced control placodes (E-G), whereas the distances varied greatly between adjacent mutant placodes (H-J). Arrows indicate fusions of mutant placodes (H-J). (K) Placode numbers calculated from E14.5 Sostdc1 wholemounts indicated a 1.6-fold increase in Catnb^ex3K14/+ mice when compared with control. Data are represented as mean±s.d. (L) The distribution of placodes according to diameter as measured from E14.5 Sostdc1 wholemounts. Mutant placodes showed larger variation in size and were, on average, smaller than control placodes. The placode was determined as the unstained area surrounded by the positive Sostdc1 expression. Number of placodes measured: mutant, n=218; control, n=137. Scale bars: 2 mm in A,A'',C; 0.5 mm in A'; 200 µm in E.