Contamination of caudal mediastinal node efferent lymph in sheep

Abstract

Many investigators have used the chronic sheep lung lymph preparation to collect caudal mediastinal node (CMN) efferent lymph. The lymph collected with the preparation has been assumed to be almost pure lung lymph. Sheep were examined for possible systemic contamination to the lymph and in each sheep 1-5 lymph vessels were found that ran from the diaphragm to the CMN. Contamination from these vessels would not be eliminated in the chronic sheep preparation. The flow rate from these vessels was 3.0 .+-. 2.6 (SD) ml/h in anesthetized sheep. This represents 25-60% of the lymph flow rate in the chronic lymph preparation. In 5 sheep, 1-4 esophageal lymph vessels that entered the CMN were located. Lymph collected with the chronic sheep lung lymph preparation contains a significant nonpulmonary contamination.