Fig. 6
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Fig. 6
Protocadherin10b is required to maintain integrity of thalamus.
Dorsal views of the left hemisphere of embryo at 42 hpf (a–c), 48 hpf (d–i), and 3 dpf (j–l) are displayed. To visualize orientation of the figures, small sketches accompany the experiments showing the thalamus (Th) in dark grey and the rostral thalamus (rTh)/pretectum (PTec) in light grey. At 4 dpf, the anatomy of the caudal forebrain is visualized by a confocal microscopy analysis of ubiquitous nuclei staining by Sytox green (m–o). At 42 hpf, gbx2:GFP expression marks the thalamus as well as the position of the diencephalic-mesencephalic border (DMB) by the position of the posterior commissure (PC). Knock-down of Lhx2/Lhx9 leads to the appearance of gbx2:GFP positive cells posterior to endogenous expression domain (b, white arrow). In embryos knocked down for Pcdh10b, thalamic gbx2:GFP cells appear similarly to (b) in the pretectum (c, white arrows). Analysis of lhx2/lhx9 morphant embryos and pcdh10b morphant embryos by a double ISH approach for lhx9/gsx1 (d–f). lhx9 marks the thalamus and gsx1 the pretectum seen in a dorsal view (d). In Lhx2/Lhx9 morphant embryos, the expression pattern of lhx9 and gsx1 intermingles (e, white arrow) similar to the phenotype observed in pcdh10b morphant embryos (f; white arrows). Confocal sectioning of lhx2/lhx9 double morphant embryos in vivo reveals mixing between Tal1:GFP positive and the neurog1:RFP positive cells in the cTh (g–h2, white arrows). A similar intermingling phenotype is detectable in pcdh10b morphant embryos at 48 hpf (i, i2). At 3 dpf, the rTh is marked by gad1 by a fluorescent ISH (j, j2). After knock-down of Lhx2/Lhx9, gad1 positive cells can be found in the territory of the cTh (k, white arrows); furthermore, in Pcdh10b-deficient embryos, gad1 positive can also be found in the cTh (l, l2). Lateral views of the caudal forebrain show three cell nuclei loose border zones: the border between prethalamus and thalamus, the ZLI (white dashed lines), the one between the thalamus and the pretectum (red arrows), and the one between pretectum and midbrain DMB (white dashed lines). The border zone between the thalamus and the pretectum is not detectable in lhx2/lhx9 morphant embryos (n). Similarly, this demarcation is also missing in pcdh10b morphant embryos (o), whereas the ZLI and the DMB are not affected. Tec, tectum; Teg, tegmentum.