Figure 2.

Assessment of the location of the initiation sites for contractions (i.e., pacemaking sites) in ex vivo preparations of popliteal lymphatic vessels: (A) A long isolated, cannulated, pressurized lymphatic segment containing 3 valves; (B) Three consecutive spontaneous contractions recorded from the lymphatic segment shown in panel A under equal upstream and downstream pressures (2 cmH₂O); the image of the vessel is rotated 90^o and aligns with the STM. (C) Analysis of each individual contraction wave shows two contractions being initiated on the downstream (top) end of the lymphatic segment, while the last contraction originates from a pacemaking site located in the opposite (i.e., upstream) end. Pacemaking sites are represented by open markers (circles). Contraction waves associated with different pacemaking sites display comparable propagation speeds; (D,E) Pacemaking location probability in vivo and ex vivo respectively; (F) Length of lymphatic segments included in this analysis. * Indicates statistical significance (p < 0.05) between groups.