A possible route for lymphocyte migration into diseased tissues

Vessels within the lymphocytic infiltrate in 161 examples of 24 different diseases have been studied using light and electron microscopy and histochemistry. Hitherto undescribed venules have been identified within lymphocyte aggregates which exhibit a structure, ultrastructure and cytochemistry previously believed to be restricted to the high endothelial venules of lymphoid tissues. The significance of these findings is discussed within the context of lymphocyte migration into abnormal tissue.