Fig. 1. Candidate cell fractions from E11.5-E13.5 embryonic organs were purified by flow cytometry and transplanted into lethally irradiated adult recipients. High-level (>5%) long-term multi-lineage contribution to haematopoiesis was determined after 24 weeks. Path `a' represents the transplantation of freshly dissected organs, whereas path `b' indicates the additional 3-day explant culture step prior to transplantation.