Investigation of glial cells in semithin sections. III. Transformation of subependymal cells into glial cells, as shown by radioautography after 3H‐thymidine injection into the lateral ventricle of the brain of young rats

Strong labeling of the cells in the subependymal layer was produced by stereotaxic injection of 5 μCi of 3H‐thymidine into the left lateral ventricle of the brain of one and a quarter month old rats weighing about 100 gm. These animals were sacrificed by glutaraldehyde perfusion from two hours to 21 days later. Blocks of corpus callosum with adjacent subependymal and ependymal layers were excised from the injected and non‐injected sides, and embedded in Epon; 0.5 μ thick sections were radioautographed and stained with toluidine blue.