Figure 7.

Analysis of neocortical gene expression in the barrel field of somatosensory cortex. One hundred micrometers sagittal sections of brain hemispheres after in situ RNA hybridization with probes against COUP-TFI, Id2, RZRβ, and Cad8. Ages examined for each gene: P6, P10, P20, and P40. Oriented with dorsal up and rostral to the left. COUP-TFI exhibits robust expression the barrels at P6, and at later ages expression is mostly restricted to barrel septa (outlines of barrels, arrows in B1, D1). Id2 expression in the layer 4 barrel field is absent at P6 (arrow in A2), but some light expression in septa can be seen at P20 (arrows in C2). RZRβ exhibits robust expression in the barrel septa and hollows at P6 (arrow in A3), and although expression continues in both septa and hollows at later ages, the septal expression become relatively stronger (arrows in B3, D3). Cad8 displays limited expression in the barrel hollows but strong expression is seen in the septa at P6 and P10 (arrow in A4). Specific barrel expression is lost at P20 and P40 (C4, D4). Scale bar = 100 μm. Adapted from Dye et al. (2011b).