Figure 6
From: Genetic interplay between the transcription factors Sp8 and Emx2 in the patterning of the forebrain
Defective preplate splitting and subplate development. (a, a') ISH for Tbr1 transcript on E15.5 coronal sections (medial is to the right). (b, b') Immunohistochemical co-detection of Tbr1 and BrdU on E15.5 sagittal sections (rostral is to the left). Mutants lack well separated/positioned Tbr1+, putative subplate cells at E15.5 (arrow and asterisk in (a, a')). At this stage, BrdU+ (injected E11) cells co-labeled with Tbr1 form a superplate-like structure by populating the upper CP/MZ in cKO (arrow in (b)). In controls, those cells settle in the subplate area (arrow in (b)). Arrows indicate the dislocation of BrdU+/Tbr1+ cells in mutants (b'). Co-detection of Reelin- and Tbr1 protein in the MZ on coronal sections at E18.5 (c, c') (medial is to the right) cKO showed more Reelin+/Tbr1+ (putative Cajal-Retzius cells) in the MZ (c'). The PPL does not split properly in cKO; additionally Gap43+ axons (assayed on E18.5 coronal sections) form bundles around the internal capsule (arrowheads in (d, d') and some project ectopically into the MZ (arrow in (d, d')).