Light microscopic localization of cytochemical reactions in epoxy-embedded material for electron microscopy

Tissues from mice were fixed in 1.5% glutaraldehyde, treated for the ultrastructural localization of alkaline phosphatase or Mg++-dependent adenosine triphosphatase, post-fixed in osmium tetroxide, dehydrated and embedded in plastic for electron microscopy. The sites of reaction were visualized in 1-mu plastic sections counterstained with toluidine blue, using a phase contrast microscope. The data show a close correlation between the sites of reaction observed with the phase contrast microscope and the sites studied with the electron microscope. The use of this technique for the study of these phosphatases in normal and pathologic tissues is recommended in order to achieve a high degree of accuracy in selecting a portion of the tissue sample for electron microscopy and to obtain greater resolution in the localization of these enzymes with the light microscope.