A modified cleansing procedure to obtain large freeze-fracture replicas

A method for cleaning freeze-fracture replicas is elaborated which avoids their rolling up and fragmentating during successive steps. Immediately after freeze-fracturing, the replicated tissue is slowly thawed from 77 K to room temperature on solid methanol. Safe passage through the subsequent cleaning steps is facilitated by using solutions of gradually increasing surface tension. After at least 24 h of fixation in methanol, the tissue is digested in half-strength bleach containing 5% ethanol. Following further cleaning in full-strength bleach, the remaining organic material attached to the replica is dissolved overnight at room temperature in 50% saturated sodium hydroxide.