Fig. 2

a Three types of endothelial junctions (left) and the corresponding electron micrographs (right). Reprint with permission from [50]. Copyright 2009, Springer-Verlag GmbH Germany. b Organization chart of whole-body lymphatic system and the routes of contrast agent administration. (i) Intradermal/interstitial administration or indirect lymphography. (ii) Intra-lymphatic administration or direct lymphography. (iii) Oral gavage of hydrophobic lipids results in uptake through the lacteals into the mesenteric lymphatics. (iv) Intravenous administration of lymphatic contrast. Reproduced with permission from [53]. Copyright 2014, American Society for Clinical Investigation. c Modes of drug or contrast entry into lymphatics from the interstitium. Lymphatic-targeted drugs delivered to the interstitial space are passively or actively shuttled into lymphatic capillaries dependent upon the chemical and physical properties of the drug or drug delivery system. Reproduced with permission from [63]. Copyright 2021, Annual Reviews