Differential expression of CASC1 genes in song nucleus LMAN of the adult male Zebra finch. (A) Photomicrograph of an in situ hybridization conducted with a probe (DV948439) that is not locus specific reveals expression of CASC1-1 and/or CASC1-2 throughout the brain (See Additional file 1: Figure S3 for details). The approximate positions for the photomicrographs shown in panels B-D are depicted by the black squares. (B-D) CASC1-1/2 mRNA is highly expressed in song nucleus HVC (B, left panel), the globus pallidus (C, left), and ependymal cells of the lateral ventricle (D, left; arrowheads). In contrast, CASC1-1, revealed by a probe that is specific to this locus, is differentially expressed in ependymal cells of the lateral ventricle (B, right panel), large likely GABAergic cells in globus pallidus (C; right), and ependymal cells of the fourth ventricle in the midbrain (D, right). The dashed rectangles in B indicate the approximate positions of the high-power photomicrographs depicting labelled cells in the globus pallidus. Anatomical abbreviations: HVC, proper name; GP, Globus pallidus; St, striatum; v., lateral ventricle. Scale bars: 100 μm.