Thymidine kinase is expressed in the SVZ and DG, and co-localizes with GFAP positive cells.

<p>Thymidine kinase (TK) positive cells are detected in the subventricular zone (SVZ) and dentate gyrus (DG) of GFAP-TK rats, but not in wild type controls. Panels A and B show controls and panels D and E show GFAP-TK rats, Panel C shows double labeling of TK (red) and glial fibrillary acidic protein (GFAP, green) in the DG of a GFAP-TK rat. Higher magnification of a segment of panel C shows that TK positive (red) cells co-localize with GFAP staining. Scale bar represents 200 µm for panels A, B, D & E.