Experience‐based Modified Sheet Plastination Protocol

Specimen preservation has been perfected over time through the application of multiple preservation techniques such as sheet plastination. Already described advantages of this technique are: reduction of risks associated with manipulation, longer shelf life and visualization of both internal and external anatomical structures through the sheets. This method represents an alternative to create models that can be used to teach Gross Anatomy especially because the final cuts obtained from this technique are similar to those seen in diagnostic images such as Magnetic Resonance Imaging or Computed Tomography. Our objective is to present a modified standardized sheet plastination protocol based on experience gained through the technique development in our laboratory and other previously released protocols. As a basis, published protocols such as: BIODUR; University of Murcia, Spain; Dalian University, China; National University, Colombia; among others were used. Since dehydration was the step with the greatest variation, three alternatives were tested: isopropyl alcohol, acetone and ethanol. Forced impregnation is done using BIODUR P‐40 resin until −15mmHg are acquired in the impregnation chamber and cayalysis is then pursued through vertical positioning of the sheets in a Near UV spectrum (NUV) light chamber. Using acetone or ethanol in addition to a longer dehydration time, requires augmented costs and reactant usage, algo, tissue sheets do not set in the center of the vertical chamber, which resulted in broken or bent sheets. Due to this, isopropyl alcohol was chosen as the best intermediate medium. Dehydration changes were made every three days with the solvent at −20°C, starting with a concentration of 95% and making the last refill at 99.8%. The, specimens were placed in a vacuum chamber with BIODUR P‐40 resin. Constant bubbling was monitored while the pressure decreased until bubbling stopped and pressure was further reduced to a minimum of 15 mmHg. Specimens were then assembled on double‐glass sheets with the help of hooks and silicone hoses in vertical shape allowing proper catalysis on both sides simultaneously. This method provided more uniform results and reduced time spent at this stage. Finally, these were placed in a NUV chamber for 72 hours. Near UV‐light was used instead of UV‐light because of the health risk of using UV light chamber in a student access‐free laboratory. In our experience, better results were obtained by making thin cuts of specimens (<6mm) since it facilitates the visualization of structures and allows the resin to remain fully translucent after being catalyzed.Likewise, results improved when using isopropyl alcohol as a dehydration method because it is less volatile allowing a gradual dehydration to limit dimensional change and shrinkage of the tissue. Support or Funding Information Anatomy Laboratory, School of Medicine, Universidad de los Andes.