[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.