2022 Volume 62 Issue 3 Pages 675-680
Transparent skeletal specimens are prepared with staining solutions such as Alizarin Red S and Alcian Blue to stain hard bones and cartilage, and then make visceral and muscle tissues transparent. There are various methods for preparing these specimens, but in general, highly toxic chemicals such as formalin and potassium hydroxide are often used. Organic solvents such as xylene and acetone, which are used to remove lipids, have a strong odor and make some students feel sick. Trypsin, used for proteolysis, and high-purity glycerin, used for clearing, are both expensive. There are thus many issues involved in routinely making specimens in science classes at junior or senior high schools. Moreover, since potassium hydroxide used in the clearing treatment is a strong alkali, it is necessary for students to be alert and take measures when it comes into contact with their skin. However, such specimens rarely disassemble the living body in the process of their production, and the three-dimensional arrangement of the bones is almost completely preserved, without losing small bones. Therefore, the specimen is a suitable teaching material for considering the positional relationship between bones and internal organs, motor function, and development. There are examples of its use in ESD (Education for Sustainable Development), in marine environmental education, and science education. In this study, we investigated a clearing reagent to improve safety and reduce costs. Specifically, papain was used instead of trypsin. We also examined various weak alkaline components and detergents instead of potassium hydroxide and glycerin. Results showed that a saturated solution of disodium hydrogen phosphate is effective for clearing.
