Fig. 4. Wnt-4 is expressed in multiple epithelial layers.

Cryostat sections of fixed, frozen heads from mice on days E12.5–E14.5 were processed for expression of Wnt-4 transcripts by in situ hybridization with either an antisense Wnt-4-specific riboprobe (A–C) or the sense (negative) control (D–F). Wnt-4 was markedly expressed in the epithelia lining the oral cavity, tongue, and palatal shelves on E12.5 (A). On E13.5, further staining was found in tooth primordia and in the submandibular duct, as well as in the palatal shelf epithelium. On E14.5, expression in the secondary palate was found in epithelia of the nasal cavity, tongue, and palatal shelf (oral and nasal surfaces). On E14.5 expression of Wnt-4 was also found in tooth primordia and in the submandibular and sublingual ducts (not shown). All panels, 100X magnification. Bar is 50 μm.