The Rapid Preparation of Frozen Tissue Sections

Abstract

The essential feature of this procedure involves the rapid freezing of the tissue following excision and keeping it frozen until the desired chemical or fixative has been applied. For freezing, either carbon dioxide or liquid air is used, as desired. The microtome knife is thoroughly cooled by taping blocks of dry ice to its surface. The cut sections, still frozen, are manipulated by a camel's hair brush so that they lie flat upon the knife. They are then transferred to a slide by a special section lifter. This has the form of a double-bottomed scoop packed with dry ice. Thus the section remains frozen while it is transferred to a clean microscope slide held at an angle above a Coplin jar of the desired reagent. The sections must be immersed just prior to melting. They curl and do not adhere to the slide if still rigidly frozen, and are distorted if immersed after melting. With this technic sections showing a minimum of cellular distortion may be obtained. Consequently, it facilitates the use of many cytological technics, chemical tests, and enzymatic studies, such as the Gomori technics, on a variety of tissues.