Endothelial glycocalyx structure in human lung.

Transmission electron microscopy was used to visualize the endothelial glycocalyx in the microvasculature of human lung tissue. Capillaries demonstrated varying levels of glycocalyx coverage, and the structure of the glycocalyx appeared to differ between vessels. (A, B, C) In this vessel, relatively consistent endothelial glycocalyx coverage across the endothelium can be seen on the left hand side of the image. (D) The endothelial glycocalyx in these vessels appears bush-like and clumped. (E) Glycocalyx that is non-uniform in appearance can be seen attached to endothelial cells and is protruding into the lumen by as much as 400 nm. Scale bars: A 0.5 μm, B, C, D 200 nm, E 100 nm. (F) Analysis of the thickness of the glycocalyx in these vessels suggests an average thickness of 135 nm, but ranging from 58 nm up to 426 nm.