Ultrastructure of the endothelial cells of blood capillaries of lymph nodes in the rat

Ultrastructure of endothelium in the rat popliteal lymph nodes has been studied. The cross section area of the capillary arterial part is 29.9 +/- 1.0, that of the venous part -- 91.2 +/- 1.6, the luminal cross section of the arterial part is 4.90 +/- 0,23, that of the venous part -- 46.8 +/- 1.1 mcm2. Nucleous-cytoplasmic ratio in the endotheliocytes of the arterial part is 1.50 +/- 0.06, that of the venous part -- 2.10 +/- 0.13. The number of microvesicles per 1 mcm of the profile length in the section of the basal surface in a plasmolemma is 1.13 +/- 0.07 both in the arterial and venous parts of the capillary, that of the luminal surface -- 1.35 +/- 0.07 for the arterial part and 0.48 +/- 0.03 for the venous part. The number of free microvessels per 1 mcm2 of the cytoplasmic cross section area is also greater for the arterial part (9.6 +/- 0.8 vs. 7.3 +/- 0.4 in the venous part). Numerical density of free ribosomes in endotheliocytes of the arterial part is 62 +/- 6, in the venous part -- 47 +/- 5 per 1 mcm2 of the cytoplasmic cross section. Numerical density of mitochondria in the venous part is 0.77 +/- 0.11 and in the arterial part -- 0.40 +/- 0.04 per 1 mcm3 of cytoplasm.