Lymphology and the Microcirculation—A Synopsis of Fourth International Congress of Lymphology Symposia
Lymph is a mirror of tissue fluid (the “milieu interieur” of Claude Bernard) as well as a barometer of dynamic microcirculatory events. This important facet of lymphology pervaded the 4th International Congress and was explored in depth in several symposia. The symposium entitled “What and Where is Lymph?” (M. Witte, J. R. Casley-Smith, F. C. Courtice, M. Papp, G. Szabo, P. J. Johnson, S. Rodbard, and A. E. Taylor) delved into the nature and location of “lymph”. The panel examined the relationships of lymph in lymphatic collecting channels to capillary filtrate and tissue fluid as well as the barriers that separate these fluids and the differences in their composition. Casley-Smith postulated a concentrating mechanism in initial lymphatic channels and proposed the existence of an “oncotic pump” to propel lymph onward (i.e., he maintained that lymph is higher than tissue fluid in protein content). Rodbard, on the other hand, introduced the concept of a “tissue module” constructed of a fibrous connective tissue capsule containing a cluster of parenchymal cells, blood capillaries, and ultrafiltrate permeating the intracapsular space. Lymphatic vessels are restricted to extracapsular clefts and intracapsular and extracapsular tissue fluid are discrete pools (i.e., Rodbard postulated that lymph is somewhat lower than tissue fluid in protein content). In contrast, Taylor’s simple mathematical model predicted that protein concentration in an upstream lymphatic vessel is essentially the same as tissue protein concentration adjacent to the blood capillary wall. He reported that a subcutaneously implanted Guyton capsule contained fluid identical in protein content to draining regional lymph. After a lively discussion, there was general agreement on at least one point—that further investigation in this area was greatly needed and direct measurements had to be made.
KeywordsLymph Flow Tissue Fluid Lymphatic Capillary Lymph Circulation Capillary Filtrate
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