Fig. 8. Six3 expression in the developing mouse retina. (A-C) Six3 is expressed in the murine embryonic retina. Immunostaining of a cryosection of E14.5 retina revealed Six3 nuclear staining in the inner neuroblastic layer (inbl), where newly postmitotic cells are differentiating (arrow), and in the outer neuroblastic layer (onbl), containing mitotic progenitor cells (open arrowhead). The expression in onbl cells is generally lower compared with that in inbl cells at this stage. A similar pattern of expression was detected at E17.5 (D-F), P0 (G-I) and P6 (J-L). Immunostaining of a 3-week-old mouse retina (M-O) revealed nuclear staining in the inner nuclear layer (INL) and ganglion cell layer (GCL) (M, arrows) and a punctuated pattern in the photoreceptors found in the outer nuclear layer (ONL) (O, arrows). PE, pigmented epithelium; H, horizontal cell; Am, amacrine cell. Scale bars: 25 µm (low magnification) and 10 µm (high magnification) in A-H,J-O; 10 µm in I.