As a licensed embalmer since 1992, I have always been fascinated by the preservation of human tissues. Preservation methods are especially important in the gross anatomy lab where students directly interact with tissues and potentially harmful chemicals. Because of the inherent risks associated with such close exposure and interaction, shouldn’t we explore techniques that might be able to reduce the risks associated with these harmful, potentially carcinogenic compounds?
In 1992, Austrian native Dr. Walter Thiel introduced a soft-fixed embalming procedure that he spent years perfecting by testing it on 1,000 cadavers. As the story goes, he noticed that meats that were cured with brine solution at a local butcher shop had a much more life-like appearance and texture as compared to the grayer and firmer cadavers that were embalmed using traditional formaldehyde. The formula he finally adopted enabled in-situ tissue to have a more pliable and life-like appearance, while it kept the carcinogenic effects to a minimum.
Benefits of Thiel’s technique include:
- The ability to position limbs and joints within their anatomical limits
- Reduced exposure to harmful chemicals
- The presence of antimicrobial and antifungal properties
- The usage of tissues in vast clinical simulated procedures (i.e. lumbar puncture and laparoscopic procedures)
- Use of ultrasonography in clinical training and teaching anatomy
- Odor reduction in the gross anatomy lab
- A more realistic experience for surgeons when cutting through the skin of a Thiel embalmed body (it is much like cutting through living tissue)
The drawbacks are:
- Salt solutions can possibly burn and discolor tissues, particularly in regions like the zygoma where some cadavers have little subcutaneous tissue over the malar bone.
- The Thiel method has histologically changed some cellular arrangement in connective tissues like tendons. Studies involving tensile stress and strain on these tissues may result in inaccurate data.
- Chemicals utilized are more expensive than traditional formalin fixed bodies.
- Although longevity is evident in the Thiel fixed body, degradation of tissue may occur sooner than in formalin fixed bodies.
The solution itself is in essence a salt mixture that is arterially injected, just as in the typically prepared formalin cadavers. This mixture is composed of the following compounds:
- Ammonium nitrate
- Potassium nitrate
- Boric acid
- Morpholine (fungicidal properties)
- Sodium sulphite
- Ethyl alcohol
- Ethylene glycol (surfactant)
- 4-Chloro-3-methylphenol (disinfectant)
In my research, I identified several U.S. institutions that use the Thiel method for preparation, but the majority of U.S. programs are still using standard formalin fixed tissues. The Thiel method, however, is more commonly used in European countries.