Fig. 7. Characterisation of Lhx6-positive columns of cells in the telencephalon. (A-D) Frontal sections through the telencephalon of 48 hpf surface fish (left) and cavefish embryos (right) showing Lhx6 and corresponding GAD65 expression in the putative migratory stream. Arrows point to the increased Lhx6 or GAD65 component in cavefish. (E,F) Horizontal sections showing that Lhx6 (E) and Nkx2.1 (F) patterns are indistinguishable at 60 hpf in the columns of cells. (G-I) DiI labelling of the olfactory projection onto the olfactory bulbs of a 7-day-old cavefish, in dorsal views, where anterior is up. G (bright field), H (fluorescence) and I (combined) photomicrographs indicate that the olfactory bulbs are located in the anterolateral part of Astyanax telencephalon, i.e. where the Lhx6- and GAD65-positive cells terminate their migration. (J-M) Hemi-sections through the telencephalon of surface (J,K) or cavefish (L,M) embryos, to illustrate Lhx6 pattern with regard to Pax6 and Lhx9. In L,M, dashed lines delineate the brain and the adjacent olfactory epithelium (oe), which also expresses Lhx9. (N) Schema, in which gene expression is indicated on the left, with corresponding anatomical regions on the right. dSP, dorsal part of subpallium; hyp, hypothalamus; n, nostril; ob, olfactory bulb; po, preoptic region; SP, subpallium; tel, telencephalon. Scale bars: 50 µm.