Differential expression of TMRA in song nucleus RA of the adult male Zebra finch. (A) Photomicrograph of in situ hybridization showing the distribution of TMRA expressing cells in a parasagittal brain section that includes song nucleus RA (~2.0 mm from the midline). (B) High-power view reveals the enrichment of TMRA in individual cells within RA. (C) Detailed views reveal that in some cells in RA (indicated by the arrowheads), labelling is largely restricted to nuclei, and expression is low in the surrounding cytoplasm. Anatomical abbreviations: A, arcopallium; H, hyperpallium; M, mesopallium; N, nidopallium; St, striatum. Scale bars: 100 μm in A and B; 20 μm in C.