Fig. 7
A subset of IC guidepost cells is misplaced in Sema6a mutant and Plxna2; Plxna4 double mutant E13.5 brains. a Schematic representation of the dye tracing experiments performed. DiI crystals were inserted into the dTh of E13.5 Plxna2 +/− ; Plxna4 +/− and Plxna2 −/− ; Plxna4 −/− mouse brains; from this position, the dye diffuses along TCAs in an anterograde fashion, and on guidepost cell projections reaching the dTh. (Adapted from Garel and López-Bendito [21].). b, c Coronal sections of E13.5 brains illustrating the labeled IC (b) and the exact location of dye placement in the dTh (asterisk in c). d–s DiI labels growing TCAs as well as guidepost cell bodies in the IC area, along the dorso-lateral path which TCAs will follow to proceed further into the subpallium (solid arrowheads), in late E13.5 wild-type (d–g), E13.5 Plxna2 +/− ; Plxna4 +/− (h–k), E13.5 Plxna2 −/− ; Plxna4 −/− (l–o), and E13.5 Sema6a −/− (p–s) mouse brains. In Plxna2 −/− ; Plxna4 −/− and Sema6a −/− sections, however, back-labeling identifies a group of cells projecting to the dTh in an abnormal caudo-ventral position in the vTel, close to the pial surface, corresponding to presumptive amygdala territories (l–s, empty arrowheads). No dye can be detected in this domain in either wild-type or Plxna2 +/− ; Plxna4 +/− brains. Scale: b, c: 250 μm; d–s: 100 μm. t Quantification and comparison of DiI signal intensities in the caudo-ventral subpallium, expressed as ventral vTel/overall (DTB and vTel) integrated intensity ratios (IRRs), between wild-type, Plxna2 +/− ; Plxna4 +/−, Plxna2 −/− ; Plxna4 −/−, and Sema6a −/− E13.5 brains. A significantly higher DiI signal intensity compared to both wild-type (n = 10) and Plxna2 +/− ; Plxna4 +/− (n = 7) measurements was detected in case of Plxna2 −/− ; Plxna4 −/− (n = 6) as well as Sema6a −/− (n = 11) specimens. IRRwild-type = 0.09 ± 0.01; IRR Plxna2+/−; Plxna4+/−  = 0.10 ± 0.02; IRR Plxna2−/−; Plxna4−/−  = 0.23 ± 0.06; IRR Sema6a−/−  = 0.20 ± 0.02; p < 0.01