otx2:venus expression in radial glia located at the ventricular zone of the adult zebrafish midbrain. (A) Schematic representation of the adult zebrafish brain. The position of the cross section of the midbrain with optic tectum, hypothalamus, and pituitary shown in panel (B) is indicated (orientation indicators A->P: anterior to posterior; D->V: dorsal to ventral). (B) Cross section of the midbrain labeled with otx2:venus (green), the radial glial marker S100 (red) and the nuclear counterstain DAPI (blue). (C) Higher magnification of the region from midbrain tectum indicated by white boxes in (B). (D) Higher magnification of an inset from panel (C) showing radial glial cells at the ventricular zone of the midbrain tectum labeled by S100 co-expressing otx2:venus. Anatomical descriptions are based on the zebrafish brain atlas (Wullimann et al., 1996). Scale bars (B): 100 μm; (C): 25 μm; (D): 2 (or) 5 μm. (B,C: maximum intensity projection; D: single Z-plane).