PHYSIOLOGIC IMPORTANCE OF LYMPH 



IO=,I 



50 



400 



fig. 4. Curves illustrating relative permeability coefficients 

 for dextrans of different molecular weights. Relative perme- 

 ability coefficient is ratio of dextran between lymph and plasma 

 divided by ratio of albumin between lymph and plasma. See 

 (141). 



with its high protein concentration emphasized the 

 importance of the hepatic lymph system in the turn- 

 over of plasma volume and plasma proteins. Little or 

 no new protein, as such, is added to lymph in the 

 liver (234), and the large amount of protein is that 

 which has leaked from blood capillaries and sinusoids. 

 Nix<7 al. (157, 158) estimated that, in the anesthetized 

 dog, the volume of lymph collected from the liver, in- 

 testine, and thoracic duct was equivalent in 24 hours 

 to 47, 39, and 95 per cent, respectively, of the es- 

 timated plasma volume. They found, as have others, 

 that more than half of the total circulating plasma 

 proteins passes through the thoracic duct daily. When 

 they produced hepatovenous congestion or cirrhosis, 

 the flow of hepatic lymph was two to five times that 

 found in normal dogs. The equivalent of 70 to 207 

 per cent of the total circulating plasma protein passed 

 through the liver lymphatics in 24 hours. Likewise, 

 Friedman et al. (78) collected hepatic lymph from the 

 rat in chronic experiments and reported an average 

 flow of 1.5 ml in 12 hours (12 rats). This rate of flow 

 was increased to an average of 5. 1 ml in 1 2 hours (6 

 rats) following biliary obstruction. 



The role of liver lymphatics in the problem of ascites 

 is discussed by Yoffey & Courtice (234). They point 

 out that in the shifts of fluid which take place when 

 ascites develops, three major sets of lymphatics are in- 

 volved: lymphatics of the alimentary tract, liver 

 lymphatics, and lymphatics of the diaphragm. All 

 three are capable of carrying very large volumes of 

 lymph, much greater than lymphatics from any other 

 region of the body. Only in extreme circumstances 

 and in the presence of severe disease does gross ascites 

 become evident. Baggenstoss & Cain (10, 11) studied 

 the relationship of hepatic hilar lymphatics to ascites 

 in man. In various conditions associated with ascites, 

 they found these structures increased in size and num- 

 ber when ascites was caused by cirrhosis of the liver or 

 congestive heart failure but not when it was caused by 

 neoplastic involvement of the peritoneum or by renal 

 disease. Other clinical and pathologic conditions asso- 

 ciated with ascites which revealed an increase in 

 lymphatic vessels at the hilus were lupus erythemato- 

 sis, fatal virus hepatitis, and massive liver involvement 

 by neoplasms. 



Pulmonary Lymphatics and Edema 



There is a very large literature on the anatomy and 

 pathology of the pulmonary lymphatic system but 

 there is comparatively little information on the func- 

 tion of the widespread lymph vessels in the lungs. 

 Warren & Drinker (216) were the first to collect lung 

 lymph in 1942 when they succeeded in cannulating a 

 large lymphatic in the anterior mediastinum of dogs. 

 In 18 animals, they reported an average lymph flow of 

 1.1 ml per hour and an average protein concentration 

 of 3.7 g per 100 ml. As they realized, their experiments 

 were subject to the criticism that the thorax was open 

 and the usual intrathoracic pressure absent. To ob- 

 viate this difficulty, they and subsequent investigators 

 turned to collection of lymph from the right duct. 

 This procedure, although eliminating the above ob- 

 jection, introduces other variables. The right duct, as 

 usually cannulated in the dog for lymphatic studies, 

 not only drains the lungs but also carries lymph from 

 the heart, right side of the thorax, and part of the 

 convex surface of the liver. It is thus difficult to quan- 

 tify the contribution of the lungs to total right duct 

 lymph flow. However, since the contribution from 

 thorax and liver are small, it is probably valid to 

 assume with Drinker (60) that "in the quiescent, 

 anesthetized dog the amount of lymph collected from 

 the right duct expresses the lymph delivery from the 

 contracting heart and moving lungs. If cardiac ac- 

 tivity is kept reasonably constant, the quota of right 



