Figure 1.

In vivo and ex vivo assessment of afferent popliteal lymphatic vessel contraction waves: (A) In vivo imaging of the lymphatic vasculature in the hindlimb of a mouse following an injection of FITC tracer into the upstream popliteal lymphatic network. Five contractions along the entire imaged lymphatic segment are represented in a two-dimensional map (Space Time Map—STM) as 5 dark vertical bands extending along the entire height of the image/map); (B) Analysis of the propagation of the contraction wavefront for each contraction using STMs allows assessment of the direction of propagation and measurement of propagation speed in vivo; (C) In vivo image of a lymphatic valve; (D) STMs of contractions from isolated, cannulated, pressurized afferent popliteal lymphatic vessels; (E) Similar to the analyses performed in vivo, automated analysis of the propagation of the contraction wavefront allowed us to determine where the contraction initiated (the pacemaking site) as well as the direction and speed of propagation. In panel E-a, notice the horizontal shift between where the contraction wavefront starts at the top of the image and where the contraction ends (bottom), which is right-shifted in the transformed image. Conduction/propagation speed is directly associated with the slope of the line that connects all the points along the propagation wavefront.