OSMIOPHILIC PROPERTIES OF LUNG TISSUE WITH METHODOLOGIC EVALUATION IN CRYOULTRAMICROTOMY

The newly improved cryo-sectioning technique for electron microscopy has proven to be very versatile for investigating the fine structure of the alveolar cell wall in the lung. This communication is concerned with a fundamental critical evaluation of the technique with particular emphasis on the osmiophilic properties of pulmonary ultrastructural details. The results indicate the following; 1) Embedding media like gelatin and bovine serum albumin are not absolutely necessary and the simple use of sucrose as well as the dry cutting method described by Tokuyasu are sufficient. 2) Regarding the application of buffer solution for fixatives, phosphate buffer showed a special property to the alveolar lining layer by the deposition of osmium grains, but not in cacodylate. 3) Uranyl acetate demonstrates a higher preservation of the phospholipid in lamellar inclusion bodies and alveolar surface layer when it is applied as a fixative after the double fixations. 4) Application of partial dehydration using graded ethanols with 60 and 90% gave a distinctive appearance in the membrane systems probably as a result of sweeping excess amount of osmium grains over the tissue proper. 5) The membrane was not disclosed as unit structure as usually observed in conventional electron micrographs in any ways of this technique applied here.