BUFFERED OSMIUM TETROXIDE (Os04) FIXATION FOR CYTOLOGICAL AND FEULGEN MICROSPECTROPHOTO- METRIC STUDIES OF HUMAN RECTAL POLYPS* BY CECILIE LEUCHTENBERGER, PH.D.,

The value of osmium tetroxide (OsO4) as a superior fixative for the structure of cells and tissues has been recognized for some time (1). However, staining of OsO4-fixed tissues with the usual histological stains such as hematoxylin and eosin (H and E) or with the Feulgen reaction has met with great difficulty in the past. Baker (2), who discusses OsO4 fixation in great detail, states tha t there is no other fixative that leaves tissues in such an unstainable state. Furthermore, according to Baker, it is difficult or impossible to stain the chromatin a different color than the cytoplasm after Os04 fixation unless another fixative is added. In the following report, evidence is presented that when human rectal mucosa and polyps are fixed with buffered OsO4 according to the method of Palade (3), x staining of paraffin sections by basic and acidic dyes results in a distinct color difference between chromatin and cytoplasm. Furthermore, the Feulgen reaction also can be carried out successfully and such OsO4-fixed Feulgenostained sections are especially suitable for microspectrophotometric determinations of desoxyribose nucleic acid (DNA) in individual cells.