Printed in U.S.A. DIETHYLENE GLYCOL DISTEARATE AS AN EMBEDDING MEDIUM FOR

Owing to its physical properties, diethylene glycol distearate is especially suited for obtaining thin sections of high quality with little or no compression. Tissues can be cut as thin as 1 Mm on a steel knife without cooling, but a water trough is essential. The wax is translucent, so that specimens can be oriented for a desired plane of sectioning. The wax is also of sufficient hardness to serve as an embedding medium for osmium-fixed material and can readily be removed from such tissue sections for rapid phase contrast studies. A general method is described for embedding and sectioning with diethylene glycol distearate wax and examples of freeze-substituted and osmium-fixed material are illus-trated. It is concluded that this synthetic wax can offer a convenient and simple means for obtaining thin sections for most aspects of high resolution light microscopy. In light microscopy, high resolution studies of well fixed tissue require thin sections of the range 0.5-2 sm so that little or no specimen material will be superimposed over the plane of interest during examination (10). The prepara