Number of marrow cells required to establish a chimera or protect against lethal irradiation.

On the left y-axis is shown the 30-day fraction survival of lethally 9.5-Gy irradiated Lewis recipients receiving NBr marrow (■) and C3H/HeN recipients receiving AKR/J marrow (○). The right y-axis shows the fraction of sublethally 7-Gy irradiated recipient Lewis rats positive for donor NBr marrow when determinations were made at 6 weeks (▪), 12 weeks (♦), and 20 weeks (▵) after grafting, and C3H/HeN recipients receiving AKR/J marrow assayed at 6 weeks only (●). The x-axis indicates cells transferred by intravenous tail injection.