Fig. 4. Characterization of the first wave of T lymphopoiesis in the developing thymus. (A) Thymus rudiment sections from E11.25, E12.5 or E14.5 embryos were stained with an anti-GFP antibody. (B) Flow cytometry analysis showed that 82.3% of total CD45⁺ mononuclear cells in the E12.5 thymus expressed RAG1/GFP. The data is representative of three independent analyses. (C) GFP⁺ cells were sorted from the E12.5 thymus, and then stained with anti-PECAM-1/CD31 followed by APC-anti-Kit, biotinylated anti-CD34 and streptavidin-PE-TR. (D) GFP⁺ cells from E12.5 or E13.5 thymus were stained with PE-anti-CD25 and APC-anti CD44.