Response of Sox2+cells to spinal cord transection. (A-L) Tadpoles were incubated with 5-bromo-2'-deoxyuridine (BrdU) between days 2 and 4 after (A-D) sham operation or (E-L) spinal cord transection. Horizontal sections from animals fixed at 4 days post sham operation (dps) or days post transection (dpt) were immunostained for BrdU (green), Sox2 (red) and DNA (blue). (E-H) Transection zone and (I-L) region rostral to transection zone. (M,N) Magnification of (J) and (L). White arrows indicate Sox2+/BrdU- cells distant to ependyma, and Sox2+/BrdU+ cells are indicated by yellow arrows. (O) Sox2 immunofluorescence on a horizontal section from tadpoles at 11 dpt. Inset: magnification of the ablation gap that contains Sox2+ cells aggregates (arrows). (P) Analysis of the percentage of Sox2+/BrdU+ over total number of Sox2+ cells from samples represented in A-L. Sox2+ cell proliferation increase at the rostral level of the transection site. Scale bars: (D,H,L) 50 μm, (N,O) 25 μm.