Influence of CHIR99021 and valproic acid (VPA) alone or in combination on chicken crypt development. (A) Growth of chicken crypts with different treatments (scale bar, 200 μm). (B) Number of live intestinal organoids obtained with different treatments. At least 15 fields were used for counting the organoids obtained with each treatment. (C to G) Relative mRNA expression of mature intestinal epithelial markers of organoids after 5 d of culture with different treatments. Experiments were performed at least 3 times and a representative one was exhibited. Error bars, SEM (n = 3 wells). a, b, c Different letters on bars mean a significant difference (P ≤ 0.05). ENR, the mixture of epidermal growth factor, Noggin and R-spondin 1; CHIR, CHIR99021, an inhibitor of glycogen synthase kinase 3. LGR5 = leucine-rich-repeat-containing G-protein-coupled receptor 5; LYZ = lysozyme; SI = sucrase-isomaltase; MUC2 = mucin 2; CHGA = chromogranin A.