A method for the simultaneous determination of plasma and cellular velocities in the microvasculature

A technique is described which has made it possible to measure plasma and cellular velocities, concurrently, in specific microvessels in which single-file cell flow exists. A dye slug, injected upstream from the vessel under observation, serves as a marker for the plasma bulk flow under specific conditions which are discussed. Both the transit of individual cells and the dye can be obtained from a frame-by-frame analysis of the motion picture film taken through the microscope. The technique can readily be automated through the use of cross-correlation methods. Although the technique has been developed in the cat mesentery, it may prove useful for the study of blood flow in other tissues as well. Some results obtained from use of the technique are presented in a companion paper.