Intraventricular AdNoggin targets viral transgene overexpression to the ventricular wall. A-C, Sagittal sections of AdNoggin-injected (A, C) or AdNull-injected (B) rat brains were treated with antisense (A, B) or sense (C) probes for mouse noggin. Expression of the viral transgene is limited to the wall of the lateral ventricle. D, Dorsal; V, ventral; A, anterior; P, posterior. Scale bar, 2 mm.