Temporal sequence of engraftment of donor-derived 3.6-blue bone lining cells in a 2.3-green recipient. Mice from the same TBI/rescue experiment were examined at days 7, 14, 21, 28, 56, and 78 after systemic transplantation. Shown here are representative images at day 14 (A, when 3.6-blue cells first appear, arrows), day 28 (B), and day 78 (C). Digital thresholding and counting of the number of 3.6-blue cells in each image was (A) 28, (B) 37, and (C) 48. (A-C) Original magnification, × 200.