Long-term self-renewal of uterine blast colony cells. (A) Schematic representation of primary and secondary BM reconstitutions. BMCs were isolated from primary recipients at 12 weeks (short-term donor) or 12 months (long-term donor) after the primary reconstitution, and then injected into a second set of lethally irradiated wild-type (C57BL/6) mice through the tail vein. At 9 days after the second reconstitution, GFP⁺ nodules were observed in the spleens of the secondary recipients (B-C; n = 6 per group). At 12 weeks, GFP⁺ cells were detected in the BM, blood, and spleens of the secondary recipients (D-E; by FACS; n = 6 per group). RT-PCR confirmed GFP mRNA expression in the BM and spleen of the secondary recipients (F-G). Control indicates wild-type BMCs (negative control); and positive, GFP⁺ transgenic BMCs (positive control).