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Fig. 2. Evolutionary conservation of the caudorostral wave of RALDH2. RALDH2 in
situ hybridization of mouse embryos from early headfold (EHF) to somite
stages. Note the sharp anteroposterior (AP) edges of RALDH2 expression in the
EHF embryo. Anterior expansion of RALDH2 in the lateral mesoderm is underway
at the 1-somite stage, but a more robust expression of RALDH2 is observed in
embryos at the 2-somite stage. At the 5-somite stage RALDH2 expression
advanced considerably in anterior lateral mesoderm. Black arrows indicate
arches of Raldh2 expression in the lateral mesoderm.