Lymphatic topology reveals a novel intranodal lympho-venous shunt

Understanding the lymphatic network is crucial for immunological research. Currently, a complete map of lymphatic drainage in mice is lacking. We present a detailed lymphatic system flow dynamic of two mouse strains with swollen lymph nodes (LNs), using region-specific tracer injection and high-resolution micro-CT imaging to characterize LN volume, weight, density, and spatial topology. No significant differences were observed in LN localization or numbers by strain or sex. Notably, we identified previously unreported drainage pathways and asymmetries, including distinct right and left lymphatic flows. We also discovered intranodal lympho-venous shunts in LNs, which facilitate unidirectional fluid transport and prevent interstitial fluid buildup and edema. Our findings suggest that these shunts may play a significant role in the delivery of therapeutics within LNs and highlight the need for further research into lymphatic structure-function relationships. © 2026 The Author(s). The Journal of Pathology published by John Wiley & Sons Ltd on behalf of The Pathological Society of Great Britain and Ireland.