Path of Escape of Vital Dyes from the Lymphatics into the Tissues

Abstract

The way in which substances of large molecule and fluids move through the tissue is unknown. To learn something of this we have studied the passage of vital dyes through living tissues, under varying physiological and pathological conditions.

Two dyes, pontamine sky blue and patent blue V, of widely different diffusibility, when introduced directly into the lymphatics of the ears of living mice 1 , 2 , 3 eventually pass out in greater or less part from the channels at situations far from the site of the injection. Their escape and subsequent spread through the tissues have been watched at high magnification with the Ultropak microscope. The dyes do not pass out in a colored cloud from the lymphatics of normal ears, but first appear as very fine, irregular, bristling or wavy lines of color, extending outward from the wall of the vessel. With a micro-probe these colored lines can be bent and twisted and with the removal of pressure they spring back to their original positions. The dye appears to be fixed either between or upon preformed tissue elements. Within a few minutes of this first evidence of escape the extravascular coloration becomes more intense, the lines wider, and their margins less sharp, as though dye were diffusing from them. Manipulation still demonstrates that the dye cannot be dislodged. But soon, with the onset of the mild edema which these dyes induce in the tissues, the coloration becomes diffuse and pressure with the micro-probe modifies its intensity and forces it from ever this may be, it is certain that the dyes move through the tissues along tracks, as it were, determined by the form and situation of the connective tissue fibers.