MEMBRANOUS COMPONENT OF ALVEOLAR EXUDATE

Double fixation in glutaraldehyde followed by osmium reveals ultrastructural details in greater clarity than with osmium alone. By means of this method the lungs of control rats and rats exposed to 100% O2 at 1 atmosphere for 1 and 2 weeks were studied. The membranous elements found in the alveolar exudate and occasionally in alveolar macrophages are described. They are composed of parallel unit membranes 85 Å in width and separated by a 420 Å space. Results of 90 degree sectioning, which gives a three-dimensional picture, are shown along with a model of three-dimensional structure. A possible origin of the membranes from the phospholipids released in cellular disintegration is suggested. © 1968 Academic Press Inc.