The functioning in unanaesthetized sheep of the popliteal lymph node after the surgical removal of its blood supply.

Operations were performed to cannulate the efferent duct of the popliteal node of sheep and, at the same time, the blood vascular system was removed surgically from the popliteal fossa so that the node was deprived of it blood supply. Twelve preparations were technically successful in that lymph flowed spontaneously from the unanaesthetised sheep for from 3 to 30 days after the operation. Eight control preparations were established in which the blood supply of the node with the cannulated efferent duct was left intact. In only four of the test preparations was the function of the node decisively impaired so that dendritic macrophages appeared in the lymph, the output of lymphocytes remained very low, and later histological examination showed the nodes to be grossly depleted of lymphocytes. In two of these four preparations the surgical devascularization of the node was aided by arterial embolization. In the remaining eight test preparations the outputs of lymphocytes in the lymph gradually regained normal values, and the nodes then responded normally to antigenic stimuli.