TFAP2A and TFAP2B cooperatively function in CNCCs during midfacial development. (A-D′) Lateral (A-D) or frontal (A′-D′) views of prenatal mice on embryonic day 18.5 (E18.5). Genotypes are as follows: CTRL (CRE-negative, any Tfap2a/b allelic combination; CRE-positive; Tfap2a+/flox; Tfap2b+/flox), Tfap2aNCKO (CRE-positive; Tfap2aflox/flox; Tfap2b+/flox), Tfap2bNCKO (CRE-positive; Tfap2a+/flox; Tfap2bflox/flox) and Tfap2NCKO (CRE-positive; Tfap2aflox/flox; Tfap2bflox/flox). n=5 per genotype. Gold arrowheads in B and C indicate snout indentations. Insets in A′-D′ include higher magnification images of the snout, with misplaced vibrissae outlined. White arrowhead in D indicates the shortened snout; the asterisk indicates mandible hypoplasia. (E) Schematic summarizing regions of Tfap2a and Tfap2b gene deletion in various craniofacial tissues and the corresponding phenotypes (middle, this study; right, Van Otterloo et al., 2018). Regions of deletion are indicated by reduced color intensity.
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