Mesenteric lymphoblast localization throughout the murine small intestine: temporal analysis relating intestinal length and lymphoblast division.

Mesenteric lymphoblasts (MLN) have a predilection to selectively localize in the lamina propria and epithelium of the small intestine. Using an adoptive transfer method, we examined the localization kinetics of these blasts in the intestinal wall with respect to their distribution from duodenum to terminal ileum and also assessed their mitotic activity by autoradiographic techniques. 3H-thymidine-labelled MLN cells were found throughout the small intestine by 6 hr post-transfer and reached a maximum frequency in this organ by 24 hr post-transfer. Donor blasts were most frequent in the duodenum and terminal ileum regions of the gut. Subsequently, the frequency of labelled cells throughout the intestinal wall declined to near zero. The apparent accumulation of MLN blasts in the gut was not related to either a temporary retention and departure from the pulmonary vasculature or to mitotic division of labelled cells in the gut wall. A model describing the relationship between MLN blast localization kinetics in various segments of the intestine was formulated.