Irradiation is not required for early localization of allogeneic donor splenocytes to peripheral lymph nodes. Splenocytes from eGFP Tg C57BL/6 mice were injected intravenously into B10.BR mice that were lethally irradiated (8 Gy; A, C, E, G) or were not irradiated (B, D, F, H) the day before cell infusion. Images captured 6 hours after infusion are shown for the indicated tissues. Tissues from 1 of 3 representative mice per group are shown. Examples of single-cell resolution are indicated by the white arrows (E, inset). Stereomicroscope was set to 10.0 × zoom factor with a 0.63 × transfer lens.