Differentiation of thalamic neurons is stalled in lhx2/lhx9 morphant embryos.
Analysis of embryos for neuronal differentiation in double morphant embryos at 48 hpf, lateral view (a, b, c, etc.), and cross-section of left hemispheres (a2, b2, c2 etc.) of the same embryo are shown. The expression domain of the neuronal precursor deltaA at the ventricular zone (VZ) is vigorously expanded in double morphant embryos (a–b2). Expression of the progenitor marker neurog1 marking the subventricular zone (SVZ, white bars) is also broadened in lhx2/lhx9 morphant embryos compared to control embryos (c–d2). However, the thalamus-specific terminal differentiation markers, id2a and lef1, are down-regulated in the mantle zone of the cTh (MZ, black bars) of Lhx2/Lhx9-deficient embryos (e–h2). The postmitotic marker gbx2 shows no alteration in the compound morphant embryos (i–j2). The number of cells expressing the pan-postmitotic neuronal marker elavl3 is strongly decreased in the double morphant embryos shown by a confocal microscope section of an transgenic Elavl3:GFP transgenic embryos (k, l). The deltaA and neurog1 positive precursor pool in the ventricular/subventricular zone (blue and green domain) expands on the expense of the post-mitotic thalamic neurons (red domain) in the mantle zone in lhx2/lhx9 morphant embryos (m, n). ETh, epithalamus; HyTh, hypothalamus; MDO, mid-diencephalic organizer; MZ, mantle zone; pTu, posterior tuberculum; VZ, ventricular zone.