Presence of human endothelial cells in Matrigel plug. (A) May-Grünwald-Giemsa staining of Matrigel cryosection. (B) DAPI (blue) and human CD31 (red) staining of Matrigel cryosections from negative control mice (no CD34⁺ transplants). (C) DAPI (blue), CD144 (green), human CD31 (red), and double CD144 and human CD31 (yellow) staining of Matrigel cryosection from mice receiving CD34⁺ transplants. (D) DAPI (blue), CD144 (green), human CD31 (red), and ASMA (red) staining of spleen cryosections. Scale bars equal 10 μm.