Lymphocyte recirculation through the non-lymphoid tissues of normal rats

Recirculation of lymphocytes labeled with 51Cr and 125IUDR was studied in the non-lymphoid tissues of normal rat. About 10% of the 51Cr and 40% of the 125IUDR-labeled cells were found in the extralymphoid tissues. The 125IUDR-labeled cells showed predilection toward the gut, lungs and skin. Migration of these cells to skin is an original observation, but the mechanism of the phenomenon is unknown so far.