Figure 1.

Thalamic activity regulates CRc prenatal distribution but not their postnatal elimination

(A) Confocal images of sections in the somatosensory cortex from E15.5 to P25, illustrating L1 dynamics of CRc labeled with ΔNp73^cre/+;R26^mT/+.

(B) Schematic representation of thalamic hyperpolarization using the Gbx2^creERT2/+ line (with an E10.5 tamoxifen administration), which drives the expression of the Kir2.1 channel in most thalamic nuclei, as illustrated at P9.

(C) Confocal images of sections in the barrel cortex at E18.5, P7, and P9 of controls and Gbx2^creERT2/+;R26^Kir2.1/+ to identify CRc as L1 Reelin⁺ cells embryonically, and Reelin⁺Prox1⁻ cells postnatally (arrowheads).

(D) Quantification of CRc density (cells/mm of L1 length) shows a striking reduction in E16.5, E18.5, and P7 mutants, whereas this difference is not observed any longer at P9 (E16.5: n = 5 controls, n = 4 mutants; E18.5: n = 5 controls, n = 8 mutants; P7: n = 5 controls, n = 5 mutants; and P9: n = 4 controls, n = 4 mutants).

(E) Schematic representation of thalamic hyperpolarization using the Sert^cre/+ line, which drives the expression of the Kir2.1 channel in the sensory thalamus from the end of embryogenesis, as illustrated at P9.

(F) Confocal images of sections in the barrel cortex at E18.5, P7, and P9 of controls and Sert^cre/+;R26^Kir2.1/+ pups to identify CRc as L1 Reelin⁺ cells embryonically and as Reelin⁺Prox1⁻ cells postnatally (arrowheads).

(G) Quantification of CRc density (cells/mm of L1 length) reveals a phenotype similar to the one observed in (D) (E18.5: n = 5 controls, n = 4 mutants; P7: n = 3 controls, n = 5 mutants; P9: n = 3 controls, n = 3 mutants; and P15: n = 3 controls, n = 3 mutants).

(H) Schematic representation of the postnatal whisker pluck (WP) procedure (left).

(I) Confocal images of sections across the barrel cortex of ΔNp73^cre/+;R26^mT/+ at P7, P9, and P15 in controls and WP conditions immunostained for DsRed (red) to label CRc.

(J) Quantification of CRc density (cells/mm length of L1) shows no differences in controls and WP pups (right) (P7: n = 6 controls, n = 3 WP; P9: n = 4 controls, n = 3 WP; and P15: n = 4 controls, n = 3 WP).

Values are expressed as means ± SEMs, ^∗p < 0.05; ^∗∗p < 0.01; ^∗∗∗p < 0.001; 2-way ANOVA test with Sidak’s multiple comparison correction. Scale bar represents 100 μm.