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Fig. 2 | Neural Development

Fig. 2

From: Semaphorin-Plexin signaling influences early ventral telencephalic development and thalamocortical axon guidance

Fig. 2

Neuroanatomical tracing experiments reveal a Sema6a mutant-like TCA phenotype in Plxna2; Plxna4 double mutant brains. a–c Retrograde labeling with carbocyanine dyes from the vTel in wild-type (a) versus Plxna2 −/− ; Plxna4 −/− P0 brains (b, c). Insertion of DiI crystals in the vTel (asterisk) results in no back-labeling of dTh neurons in wild-type brains; on the other hand, in Plxna2 −/− ; Plxna4 −/− brains DiI back-labels thalamic axons and cell somas located in the dLGN (b), a finding that coincides with data obtained from Sema6a −/− brains. In addition, dye-labeled neurons are also found in the VB, indicating the extension of guidance defects to a subset of thalamic axons normally directed to somatosensory cortical areas. d–i Back-labeling of thalamic neurons with two distinct carbocyanine dyes from the visual (occipital) cortex and the somatosensory (parietal) cortex in P0 wild-type (wt) and Plxna2; Plxna4 double mutant (dKO) brains. c Schematic representation of the cortical sites of dye placement in P0 brain hemispheres (OB: olfactory bulb). DiA (green) and DiA (red) crystals are placed respectively on parietal (Par) and occipital (Occ) regions of the cortex. e–h Insertion of DiI crystals in visual cortical areas of Plxna2 −/− ; Plxna4 −/− brains results in the back-labeling of some thalamic neurons of the dorso-lateral VB (h), rather than the dLGN (as instead observed in wild-type brains (f)), suggesting a miswiring of somatosensory TCAs to the visual cortex similar to that present in Sema6a mutants. Normal connectivity between ventro-medial VB neurons and the somatosensory cortex is preserved, as indicated by back-labeling of these cells by DiA. Scale: a, b: 250 μm; e–h: 500 μm

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