The Effect of Incomplete Fixation of Elastin on the Appearance of Pulmonary Alveoli

Pulmonary alveolar geometry in histological sections prepared by quick-freezing the lung, with freeze-substitution of ice, fixation of the dry lung with osmium tetroxide in nonaqueous and nonpolar solvent and celloidin embedding is remarkably different from the geometry seen in preparations made by instilling aqueous aldehyde or osmium tetroxide solution in the airways. The alveolar walls in the quick-frozen lung are linear; those in the others are wrinkled. The difference was demonstrated to be due to incomplete fixation of elastin.