Cubilin mutants display anomalies in the epithelial morphology of embryonic endoderm. Shown are H&E stained sections of wild-type (A, Cand E) and mutant (B, Dand F) 8–8.5 dpc embryos. Embryos in panels A and B are oriented such that anterior is to the right and posterior is to the left. BI, blood island; S, somite; EE, definitive embryonic endoderm; VE, yolk sac visceral endoderm, Asterisk points to aberrant epithelium in place of the normal EE. Bars in A-F = 100 μm.