NONAQUEOUS FIXATIVE PRESERVES MACROMOLECULES ON THE ENDOTHELIAL-CELL SURFACE - AN IN-SITU STUDY

A fixative composed of 1% w/v osmium tetroxide dissolved in a fluoroca rbon (FC-72(TM)) was used to perfusion-fix rat blood vessels for this ultrastructural study. With non-aqueous fixation, the lumenal surfaces of endothelial cells in cardiac and skeletal muscles retained an extr acellular coat which was morphologically consistent with glycocalyx. V enules displayed the greatest density and depth (up to 870 nm thick) o f glycocalyx, but all vessel types had at least 70 nm of surface coat. The results indicate that non-aqueous fixatives will be useful in stu dies of the endothelial cell lumenal surface, while offering excellent preservation of general ultrastructure.