Tracers clear through lymphatic vessels at the caudal end of the spine. (A) Representative pictures of P40D680 tracer within Prox1-GFP⁺ lymphatic vessels in the dorsal aspect of the sacral spine. Images were acquired 60 min after P40D680 i.c.v. infusion in awake group mice. Scale bars, 1 mm (upper row); 2 mm (lower row). (B) Representative pictures of P40D680 tracer within Prox1-GFP⁺ lymphatic vessels running parallel along the ventral aspect of the lumbar spine. Scale bars, 1 mm. Data are representative of three independent experiments. (C) Schematic of lymphatic vessel routing from dorsal aspect of the caudal spine to sacral LNs. A route along subcutaneous lymphatic vessels from the base of the tail to inguinal LNs is also typically observed. (D) Schematic of lymphatic vessel routing on ventral aspect of the caudal spine to caudal mesenteric and iliac LNs.