Figure 6: Thalamic Rorβ modulates the development of the somatosensory system and axonal branching.

(a) vGlut2-immunostaining in tangential sections of the PMBSF from control Nestin^+/+;Rorβ^fl/fl (n=8) and Nestin^Cre/+;Rorβ^fl/fl (n=7) mice at P8. (b) Quantification of the total PMBSF area shown in a (**P=0.0031; Two-tailed Student’s t-test). (c) Plot of each individual barrel area and quantification of individual barrel area in control Nestin^+/+;Rorβ^fl/fl (n=8) and Nestin^Cre/+;Rorβ^fl/fl (n=7) brains (***P<0.001; Two-tailed Student’s t-test). Insert describes the barrels that are significantly reduced in the double mutant mice. (d) Fluorescence images and representative drawings of thalamic neurons from E14.5 mice transfected with i-Gfp (n=33 neurons from three independent cultures) or Rorβ-i-Gfp (n=29 neurons from three independent cultures) and analysed at 10 days in vitro (DIV). (e) Quantification of branches per neuron at increasing branch orders (***P<0.001 for second, third and fourth branch orders; Mann–Whitney U-test). Quantification of the total neurite length per neuron (***P<0.001; Mann–Whitney U-test). (f) Flattened tangential sections showing vGlut2-immunostaining in S1 at P6 after Rorβ-i-Gfp (n=5) electroporation compared with control i-Gfp electroporated brains (n=4) at E11.5. Thalamic Rorβ overexpression induces the increase on the size of the individual barrel area. (g) Quantification of the individual barrel area at P6 in i-Gfp-electroporated and Rorβ-i-Gfp electroporated brains (*P=0.02; Mann–Whitney U-test). Insert describes the barrels that are significantly expanded after Rorβ-i-Gfp electroporation. (h) Coronal sections showing the axonal arborization of individual VPM neurons in a single barrel (immunolabelled with vGlut2) after electroporation with i-Gfp (n=12 neurons from four brains) or Rorβ-i-Gfp (n=12 neurons from nine brains). Right panel: example of single axons reconstruction under the two conditions. (i) Quantification of the axon terminal length and the area occupied by the axon terminals shown in h (**P=0.003 and **P=0.009; Two-tailed Student’s t-test). Graphs represent mean±s.e.m. Scale bars, 300 μm for a and f, 100 μm for d and 20 μm for h.