Fig. 6.

Enlarged arteriovenous connections developed on the meningial surface and in the parenchyma of mutant brains. (A and B) X-gal staining of ephrin-B2^+/tLacZ brains revealed the middle cerebral artery (MCA, red arrowheads) on the lateral side of the brain. High magnification image of the boxed area in B shows direct arteriovenous connections (black arrowheads) between arterial branches of the MCA (A) and venous vessels (V) in Tie2-tTA;TRE-int3;ephrin-B2^+/tLacZ mice (B′). (C and D) Fluorescent images of sagittal cerebellar 100-μm thick sections show enlarged connections (white arrowheads) between GFP-labeled interfolial arteries of Tie2-tTA;TRE-int3;ephrin-B2^+/tLacZ mice (A) and draining veins (V) in the mutant (D) and not control (C). (Scale bar, 50 μm.)