Comparative Dll4 expression in intermediate and late-stage wholemount embryonic brains. (A1-B9) β-gal activity in the E12.5 embryonic brain of (A) Dll4lacZ/+ and (B) Dll4-BAC-nlacZ mice. A1-A3 and B1-B3 show representative wholemount images of the brain from superior, inferior, and sagittal planes. A4-A9 and B4-B9 show representative coronal sections through the brain, from anterior to posterior. (C1-D9) β-gal activity in the E14.5 embryonic brain of (C) Dll4lacZ/+ and (D) Dll4-BAC-nlacZ mice. C1-C3 and D1-D3 show representative wholemount images of the brain from superior, inferior, and sagittal planes. C4-C9 and D4-D9 show representative coronal sections through the brain, from anterior to posterior. (E1-F9) β-gal activity in the E18.5 embryonic brain of (E) Dll4lacZ/+ and (F) Dll4-BAC-nlacZ mice. E1-E3 and F1-F3 show representative wholemount images of the brain from superior, inferior, and sagittal planes. E4-E9 and F4-F9 show representative coronal sections through the brain, from anterior to posterior. ACA, anterior cerebral artery; AIC, anterior inferior cerebellar artery; azACA, azygos of the anterior cerebral artery; BA, basilar artery; ICA, internal carotid artery; MCA, middle cerebral artery; PCA, posterior cerebral artery; SCA, superior cerebellar artery; VA, vertebral artery. Units depicted are in μm.