Excess tissue material, not necessary for patient diagnosis or pathological assessment, is collected under a waiver of consent or from patients who have consented to a research study. The standard procedure for tissue harvesting includes fixation in 10% neutral buffered formalin (NBF). Fixation helps to preserve tissues from decay and autolysis by halting biochemical processes, such as the digestion of proteins by proteolytic enzymes, and protects the sample from bacterial contamination. Fixation also increases the mechanical strength and stability of the treated tissues, which helps maintain cell morphology and provides a hard surface for sectioning. For these reasons, 10% NBF is routinely used to fix tissues for a variety of research applications.