Fibroblast growth factor (FGF)-10 antagonizes the effect of retinoic acid (RA) on exocrine differentiation and branching morphogenesis. Two-day pancreatic buds were cultured for 3 days without treatment (A, E), or with 10 μg/ml FGF-10 (B, F), with 1 μM RA (C, G), with 10 μg/ml FGF-10+1 μM RA (D, H). Buds were fixed and stained for (A–D) Insulin (green)/amylase (red), (E–H) Amylase (green)/Pan-cytokeratin (red).