Fig. 5. α6 mRNA is distributed most prominently within deep cortex. Dark-field photomicrographs show the distribution of α6 cRNA labeling in select brain regions. A, Labeled cells are distributed in the anterior olfactory nucleus (aon), but not rostral piriform cortex (pc) or tenia tecta (tt). B, Shown are labeled cells in layer 2 of entorhinal cortex (ec) and the ventral endopiriform nucleus (en) (broad arrow inB, E, and F indicates the rhinal fissure). C, High-magnification photomicrograph showing labeled cells (arrowheads) just above the white matter in retrosplenial cortex; note that smaller, more densely Nissl-stained cells are not autoradiographically labeled.D, Section through rostral forebrain showing the distribution of labeled cells above the cortical white matter (arrowhead) extending ventrolaterally into the endopiriform nucleus (en) and the absence of clear labeling in the olfactory tubercle (ot) and caudate putamen (CPu). E, F, Photomicrographs of sections through caudal hippocampus (E) and the more caudal subiculum (F) showing labeled cells in (1) the deepest layers of neocortex (arrowhead) and allocortex, (2) entorhinal cortex (ec), (3) caudal hippocampal stratum granulosum (sg), and (4) subiculum (sub).G, Section through rostral hippocampus showing faint labeling in CA2 stratum pyramidale (arrow) and denser labeling in the overlying deep neocortex (arrowhead;sg, stratum granulosum; h, hilus).H, Section showing labeling of the reticular thalamic nucleus (rt). I, J, The same field of paravermal cerebellum is shown with dark-field (I) and bright-field (J) illumination to show labeling of the Purkinje cell layer (arrow in I) relative to the Nissl-stained cytoarchitectonics (J) (gc, granule cell layer inI). K, L, Sections showing labeling of the facial motor nucleus (VII) and the subfornical organ (sfo). Scale bar (shown in A):A, 480 μm; B, 685 μm;C, 60 μm; D–F, 1.25 mm;G, H, L, 600 μm;I, J, 400 μm.