The passage of radioactively tagged tracers, injected at elevated pressures, through the lymph node-venous communication coincides with the increased pressures of injection and subsequent nodal palpation in dogs. Passage of iodinated I 125 serum albumen (ISA) indicates that direct lymph node-venous communications are present, whereas passage of nucleated erythrocytes requires a communication structure the size of a capillary or larger.
Experimental observations and lymph node morphology are consistent with the concept of a mixing chamber with a dual pressure-related exit. Standardization of recovered sample volumes indicates the profiles of ISA recovery are not volume dependent. Experimentally elevated pressures of injection appear to mimic abnormal "downstream" lymphatic obstructions or local nodal pressure increases caused by regional tumor infiltration, digital nodal manipulation, or both.