Adult tissues are amenable to topographically restricted cell targeting. (A-C) Adult forebrain slice explants (R26R strain), exposed to a 1 μl drop of 100 ng/μl H3NC, displayed reporter β-Galactosidase activity (blue staining, arrows) throughout brain regions. Boxed area in A is observed at higher magnification in B. Dashed lines in B encompass periventricular layers. (C), higher magnification in the striatum. The arrow points to representative recombinant cells arranged as glomerula. (D) Fragment of adult cerebellum explants (TGZ strain) exposed to H3NC (100 ng/μl), displayed reporter alkaline phosphatase immunopositive cells, most of which appear arranged in a laminar organization suggestive of Purkinje cell layer. The arrowheads point to representative recombinant cells within the Purkinje cell layer, while the arrows indicate rare positive cells outside of it. For the whole figure, the scale bar in A represents: A, 1600 μm; B, 800 μm; C, 130 μm; D, 3000 μm.