Fig. 2. Differential expression of CD34 and CD45 in human embryonic and fetal tissues. Dissociated cells were double-stained with FITC-anti-CD34 and PE-anti-CD45 MoAbs and analyzed by flow cytometry. Distinct CD34⁺ CD45⁺ and CD34⁺ CD45^– cell subsets were observed in the 26-day yolk sac (B), 32-day AGM region (C), 32-day embryonic liver (D) and 24-week fetal bone marrow (E). In 52-day lungs, only CD34⁺ CD45^– cells were present (A).