Figure 1.

Notch pathway genes are upregulated after spinal injury. In situ hybridizations of spinal cross sections at 14 dpl are shown. Central canal is indicated by asterisks; dorsal is up. In B–D, arrows indicate single positive cells and bars delineate expression domains. A, Timeline for all experiments. B, After a lesion, her4.1, her4.5 and her9, but not her8a, are upregulated in specific areas of the ependymal zone. C, After a lesion, notch1a and notch1b are upregulated in specific regions of the ventricular zone. Notch2 shows weakly increased expression. D, After a lesion, jagged1b is upregulated only in the dorsal midline, whereas deltaC is upregulated preferentially in cells around the ventral half of the central canal, including cells that are one cell diameter distant from the central canal. DeltaA is not detectably expressed. E, Colabeling of transgene and in situ hybridization signal (arrows) indicates her4.1 and notch1b expression in olig2:GFP⁺ ventricular progenitor cells, and deltaC expression in HB9:GFP⁺ motor neurons. Scale bars, 25 μm.