M. Fischer et al., FLOW VELOCITY OF SINGLE LYMPHATIC CAPILLARIES IN HUMAN SKIN, American journal of physiology. Heart and circulatory physiology, 39(1), 1996, pp. 358-363
The purpose of this study was to investigate the previously unknown fl
ow velocity in single lymphatic capillaries of humans in the supine po
sition. Fifteen healthy subjects (10 women and 5 men; mean age 35.8 +/
- 13.1 yr) were studied. Ten microliters of fluorescein isothiocyanate
-dextran (150,000 mol wt) were injected into the subepidermal layer of
the foot dorsum. The filling of the microlymphatics from the resultin
g depot was visualized by fluorescence video microscopy and stored on
videotape. Flow velocity in the microlymphatics was determined on the
video screen by direct measurement of the advancement of dyed lymph du
ring a given time. The following median velocities were obtained: 0.51
mm/s (0.27 and 0.61 mm/s for lower and upper quartiles, respectively)
for velocity during initial network filling and 9.7 mu m/s (6.9 and 1
4.2 mu m/s for lower and upper quartiles, respectively) for resting ve
locity at the end of the filling period. Mean lymphatic capillary diam
eter was 54.8 +/- 8.2 mu m, and mean network extension was 8.3 +/- 3.2
mm. The high filling velocities are probably due to increased interst
itial pressure and volume caused by dye microinjection, whereas the va
lues measured during the end of network filling seem to approach resti
ng flow velocities.