Fig. 5. Expression of Nap1 during development. (A) Nap1 protein was present in the epiblast (arrow) and visceral endoderm (arrowhead) in transverse sections of E6.5 embryos. (B) Nap1 is present in all three germ layers in transverse sections of E7.5 embryos, and is enriched in the apical region of the epiblast. (C-E) Nap1 was present in all embryonic structures in sagittal sections of E8.0 embryos (C) and was expressed in all tissues in transverse sections of E8.5 embryos (D,E). At E8.5, Nap1 was enriched in both apical and basal regions of the cells in the neural tube (D,E); based on the Nap1 mutant phenotypes, it is likely that this localization of Nap1 is required for neural tube closure. Anterior is to the left in A-C and dorsal is up in D and E. Scale bars: 100 µm.