Lymphatic clearance of radioactive sulfur colloid.

Lymphatic clearance of radioactive sulfur colloid is measured in the hind limb of five mongrel dogs. A solid state Si(Li) detector is placed onto the skin to continuously record activity over the site of subcutaneous injection. Decrease in activity follows an exponential decay which is modeled as a dual decay occurring from both the radioactive decay of the tracer and the lymph clearance of the tagged sulfur colloid. The calculated decay constants for lymph clearance flow per tissue volume result in a mean value of 0.233 +/- 0.077 ml/hr/ml which is consistent with results of other investigators. Adjacent lymph nodes are monitored with a scintillation detector to show that the colloid is absorbed by the lymph vessels. The carotid artery and liver are similarly monitored to show that there is little or no capillary absorption of the tagged colloid.