Overlapping expression of Erg mRNA transcripts occurs in the reticular thalamus, cerebellum, hippocampus, and olfactory bulb. A, ISH with erg1 antisense probe. Note that erg1 expression was relatively weak with the exception of the reticular thalamic nucleus (Rt). Weaker expression was found in the cerebral cortex (Cx), hippocampus (Hipp), thalamus (Th), and ventral medial hypothalamic nuclei (VMH). B, ISH with erg3 antisense probe. Erg3 expression was strong in the cerebral cortex (Cx) and the CA1 subfield of the hippocampus (CA1). Weaker erg3 expression was also found in theRt and the VMH. C–D, Expression of erg1 and erg3 mRNA in cerebral cortex.C, High magnification of the cortex in Ashowing weak erg1 expression throughout cortical layers II–V.D, High magnification of B showing strong erg3-positive neurons in layers II/III and V. E,F, Expression of erg1 and erg3 transcripts, respectively, in the cerebellar cortex. Note that both transcripts were found in the Purkinje cell layer (PL). Comparison at low power revealed that only erg1 was found in the granule cell layer (E, F, top panels).G, Colocalization of erg1 (top), erg2 (middle), and erg3 (bottom) in the olfactory bulb. Erg1 and erg3 transcripts were located in neurons of the internal granule layer (IGr), mitral cell layer (Mi), and periglomerular layer (GL). Erg2 transcripts, however, were located only within the mitral cell layer and the periglomerular cell layer. Scale bar (shown inG): A, B, 2000 μm;C, D, 200 μm; E,F (top), 720 μm; E, F (bottom), 360 μm; G, 500 μm.