ABSTRACT
The purpose of fixation is to stabilize and preserve tissue, a goal which is not difficult to achieve unless investigator are dealing with an organ of continuously changing morphology. It is possible to fix lungs by "in situ" procedures. Since the appearance and dimensions of the organ depend on the way it has been fixed, interpretation of lung histology requires an understanding of the physiology of the organ. The worker will have a choice between the two most popular methods of fixing the lung: instillation and vascular perfusion. For all practical purposes, the current picture of cells and tissues in the lung and in other organs is that conveyed by chemical fixation with glutaraldehyde and osmium. On the other hand, only osmium is needed when no subcellular studies are planned, because it is in the fixation and visualization of organelles and filaments where the additional use of glutaraldehyde is beneficial.
