A fine structural study of variations in protein concentration in lacteals during compression and relaxation.

The ratios of plasma proteins and ferritin (introduced into the gut) were determined between the jejunal lacteals and the interstitial channels in puppies. This was done by fine structural densitometry and the counting of molecules, respectively. In the normal state this ratio was approximately 2. In portions of tissue whose smooth muscle had been relaxed by atropine the ratio was approximately 1; in others, where the muscle had been contracted by Carbacol, it was approximately 3. These latter correspond approximately to the filling-phase and the emptying-phase of the initial lymphatic cycle, respectively. Thus the evidence was strengthened for an hypothesis, which holds that the filling is caused by the high effective colloidal osmotic pressure of the concentrated lymph.