Comparative analyses of the color hue and stiffness properties of organ specimens fixed by immersion into formalin solution and ethylene glycol-methanol-phenol mixture.

When applying embalmed cadavers and organ specimens to gross anatomy practice and surgical training, their qualitative properties serve as important functional indices of how closely they resemble the living state. Among these properties, color hue and stiffness change remarkably after fixation. In the present study, we evaluated the properties of rat organs, including the brain, lung, liver, and skeletal muscle, after fixation by immersion in a 10% formalin solution and a non-formalin fixative, ethylene glycol-methanol-phenol (EMP) mixture. The colorimetric L*a*b* values, which are indicators of the lightness and chromatic components, showed that, compared with formalin fixation, EMP fixation significantly increased lightness in the lungs and livers, suggesting decoloration as a result of hemolysis and hemochrome elution, whereas deposition of a reddish pigment was induced in the brains and skeletal muscles. The ΔE values, the total color difference from the unfixed state, were higher in the EMP- than in the formalin-fixed livers. The biomechanical parameters for stiffness indicated that the EMP-fixed brains were hardened similar to those fixed by formalin, while the other EMP-fixed organs were significantly hardened compared with their formalin-fixed counterparts. These findings suggest that EMP fixation exerts a beneficial effect by enhancing reddish coloration, especially in the skeletal muscles, and would be useful for reducing the total amount of highly toxic formalin used in gross anatomy practice.