Figure 1.

Presence of green fluorescent protein (GFP)+ bone marrow hematopoietic stem cell–derived cells in lung tissue after bone marrow transplantation. Frozen lung tissue sections examined by fluorescence microscopy without the use of antibody staining reveal GFP+ cells easily detected in the lung tissue of recipient animals after transplantation of GFP+ bone marrow cells (representative section and flow cytometry shown in B and D, compared with recipient controls in A and C that did not receive GFP+ cells). The majority of GFP+ cells are CD45+, indicating their hematopoietic lineage. A small fraction (0.48% of all live lung cells analyzed in B do not express CD45. Br = bronchus; CTL = control; PI = propidium iodide. *Vascular lumen