An Application of the Frozen Sectioning Technic for Cutting Serial Sections Thru the Brain

The availability of CO₂ ice makes it practical to cut large blocks of cerebral tissue by the freezing method. If the tissue is first treated with 20-30% ethyl alcohol for sufficient time to secure uniform penetration of the alcohol (about 24 hours), formation of hard ice crystals can be controlled and serial sections 25-100 μ thick can be cut with negligible loss. The alcohol can be added to the fixative used for perfusion, or it can be added at any time later in the firing process, or after fixation is completed. The sections are cemented to the slide and groups of slides are manipulated thru staining processes in glass trays. Ordinary cell and fiber stains give satisfactory results. The method is particularly useful for certain neurophysiological purposes such as defining the location of electrode tracks and lesions and certain types of retrogrades. The Prussian blue test for electrolytically deposited iron can be conveniently applied in conjunction with other stains, to determine the point at which a given action potential response was observed, if steel electrodes are used.