Purified CCE-25–c-Kit^neg cell growth in RAG-2^–/– mice. CCE-25–c-Kit^negSca-1^pos and Sca-1^neg cells were purified by elutriation and cell sorting as described in “Materials and methods.” These cells were transplanted into sublethally irradiated RAG-2^–/– mice (4.0 Gy). At 14 weeks after transplantation, the thymuses were harvested and assayed for the presence of donor (Ly 5.2) thymocytes (CD3ϵ). Animals received transplants of saline (A), 1 × 10⁶ whole bone marrow (wBMC, positive control) (B), 1 × 10³ CCE-25–c-Kit^negSca-1^pos (C), or 1 × 10³ CCE-25–c-Kit^negSca-1^neg cells (D). These results are representative of 5 animals per group and 2 separate experiments.