Extended Data Figure 3: Retinoic acid posteriorizes foregut endoderm.

a, Lineage diagram that summarizes the patterning effects of noggin and retinoic acid in the formation of both anterior and posterior foregut endoderm (aFG and pFG, respectively). b, Bright-field images show that retinoic acid increased the number of spheroids that are produced from foregut monolayer cultures. c, A lower power image of Fig. 1d showing immunofluorescent image of an E8.5, 14-somite stage embryo with Hnf1β protein localized to the posterior portion of the foregut. Boxed region of embryo is shown in Fig. 1d. d, qPCR analysis of gene expression in foregut spheroids treated with retinoic acid. Posterior foregut markers HNF1B and HNF6 were robustly induced by 24-h exposure to retinoic acid. Although retinoic acid induced posterior foregut gene expression it did not induce expression of the posterior marker CDX2. *P < 0.05; Student’s t-test; n = 3 biological replicates per condition, data representative of 3 independent experiments. Scale bars, 1 mm (b) and 100 μm (c). Error bars represent s.d.