Upper limb lymphatic mapping and quantitative functional analysis in normal cynomolgus monkeys using indocyanine green near-infrared fluorescence lymphography

The lymphatic system supports immune transport and fluid balance, and disruption of upper-limb lymphatic drainage can contribute to chronic lymphedema. However, baseline information on normal upper-limb lymphatic pathways and pumping function remains limited in physiologically relevant large animal models. In this study, indocyanine green near-infrared fluorescence lymphography was used to map superficial lymphatic drainage and assess lymphatic contractility in 10 upper limbs of five healthy cynomolgus monkeys. Superficial collectors consistently converged toward the axillary lymph node through pathways aligned with the cephalic and basilic veins, and no major superficial drainage was visualized on the lateral surface of the upper limb. Volar lymphatic flow merged with radial or ulnar pathways without forming an independent route. Quantitative analysis demonstrated measurable lymphatic pumping activity, and contractility measures remained stable at 5, 10, and 15 min after injection. Transit time measurements showed substantial interindividual variability. These findings provide baseline anatomical and functional reference data for superficial upper-limb lymphatics in cynomolgus monkeys and support fluorescence lymphography as a practical approach for quantitative assessment in nonhuman primate upper limbs.