Percentage of male DNA in BM of individual recipient female mice. Female mice received 2,600 Rh/Hoe^dull marrow cells and were sampled 6 weeks posttransplant. Southern blots were labeled using a Y chromosome-specific probe and the percentage donor calculated by phosphorimage analysis, taking the male as 100% and the female as 0%. Loading variability was corrected using a probe for IL-3.