Fig. 2. Expression of STAT3 in the embryonic mouse brain. Brain sections from embryos at E13.5 (A-C,G,H,K-M,Q) or E16.5 (D-F,I,J,N-P,R) were immunostained with anti-STAT3 together with anti-nestin or anti-ßIII-tubulin (TuJ1), as indicated. STAT3 was expressed in nestin-positive cells (A-F,H,J), but not in cells positive for the neuronal marker TuJ1 (G,I). K and N show the phase-contrast micrographs of the sections. STAT3 was expressed in cells in the VZ and apical side of the IMZ at E13.5 (K-M,Q) and in the VZ, SVZ and the apical side of the IMZ at E16.5 (N-P,R). Q and R show magnification of cells expressing STAT3 (arrow) in the VZ and IMZ in L and in the VZ, SVZ and IMZ in O, respectively. In-situ hybridization analysis of the E13.5 mouse brain revealed that STAT3 mRNA was present in the neuroepithelium of the telencephalic plate (S). Dorsal side is up in A-J,S and left in K-R. Scale bars: 400 µm in A,S; 40 µm in G,K,N,Q,R.