The Breakdown of Lymph Transport.

Abstract

The method described in a preceding paper to render visible the lymphatics coursing through normal tissue has provided us with the opportunity to study the permeability of the lymphatic wall under pathological conditions. Lymphatic permeability is greatly altered by slight causes, as can be shown by following the escape into the tissue of vital dyes ordinarily retained within the lymph channels.

When Pontamine blue or Chicago blue 6B, dyes having the requisite character, are introduced into the lymph, one sees the lymphatics of the ear as dark blue channels much broader in general than the blood vessels, and having the alternation of pear-shaped dilatations and constrictions seen in specimens injected after death. Their outlines are sharp because the dye does not pass from them into the tissue that they traverse. But a mere gentle stroke across their course, with a blunt instrument, at this time or just prior to the dye injection, results in an immediate escape of color into the region directly affected. This escape is closely localized to the line of the stroke and it endures for some minutes.

Greater degrees of disturbance of the lymphatics have proportional results. When unfiltered light from an arc is allowed to fall for a fraction of a minute upon a small area of the ear, there results an immediate and abundant escape into the tissue of the colored lymph. A similar phenomenon is to be seen when local inflammation has been produced with xylol.

These observations prove that the lymphatic wall becomes more permeable upon relatively slight stimulus, letting substances through into the tissues, which ordinarily it would retain. That the small blood vessels do this upon occasion is well known; and the process is held to be mainly responsible for urticaria, especially factitious urticaria.