What Are The Steps Involved in Preparing Plastinated Animal Viscera Specimens?

Plastination is a method of preparing experimental materials using plastination technology. After fixation, dehydration and degreasing, vacuum impregnation and plastination, and shaping, the specimens are ready for teaching or other experimental purposes. So, what are the steps involved in preparing plastinated animal viscera specimens? 

 

 

1. Plastinated Animal Viscera Specimens - Visceral Specimen Material Processing

Visceral specimens used for plastination are processed according to routine dissection procedures. For lungs, after formalin fixation, the trachea or bronchi should be preserved, and the hilar structure should be preserved as intact as possible. For the heart, blood clots should be removed from the cardiac chambers. The aorta, pulmonary artery, anterior and posterior vena cava, and pulmonary veins must be preserved, and fenestration should be performed to facilitate observation of the heart structure. For hollow organs like the intestines, their contents should be removed as much as possible.

 

2. Bleaching of Plastinated Animal Viscera

Specimens dehydrated and defatted with acetone will darken in color if exposed to air for too long, requiring bleaching. Immerse the viscera specimens directly in a 1%–2% hydrogen peroxide solution for one week.

 

3. Dehydration of Plastinated Animal Viscera

Before dehydration, rinse the viscera specimens continuously under running water for an extended period, using gentle movements. Begin dehydration after 48 hours. Immerse the specimens in a gradient of 80%, 95%, 100% I, and 100% II ethanol solutions, soaking them in each solution for one week. The ethanol should completely submerge the specimens.

 

4. Degreasing of Plastinated Animal Viscera

After dehydration, the specimens should also be degreased. Ethanol only has a dehydrating effect, while acetone has both dehydrating and degreasing effects. After dehydration with 95% ethanol solution, visceral specimens can be further dehydrated and defatted with 100% acetone for 10 days at room temperature.

 

5. Animal Visceral Plastination - Vacuum Plastination

After dehydration and defatting, the visceral specimens are immediately immersed completely in a polyethylene glycol solution with a molecular weight of 600. An iron block can be used to press the specimen down in the plasticizer. The temperature is maintained at 25°C~30°C. The entire plasticization process is completed under vacuum drying and intermittent negative pressure. At the beginning of immersion, the specimen is placed in the plasticizing container containing the plasticizer. Many bubbles will appear on the surface of the plasticizer. Due to the large number of bubbles, vacuuming is not recommended at this stage; allow 12~24 hours before vacuuming. On the first day, the pressure was gradually adjusted from 70 kPa to 50 kPa; on the second day, from 50 kPa to 40 kPa; on the third day, from 40 kPa to 30 kPa; and on the fifth day, gradually adjusted to 10 kPa, maintaining a constant pressure of 10 kPa thereafter. At this point, the specimen is essentially filled with plasticizer. Each time the air inlet valve is adjusted, the amount of bubbles generated on the surface of the plasticizer must be carefully observed. Throughout the plasticization process, the number of bubbles should be controlled at 10-20 per half-minute, and later, the number should be less than 5 per half-minute, until no more bubbles are generated, thus completing the vacuum plasticization process.

 

6. Animal Visceral Plasticized Specimens - Specimen Shaping

Polyethylene glycol with a molecular weight of 6000 is placed in a 59°C constant temperature drying oven. After it is completely melted, the specimen is transferred in and completely immersed. After 10-12 hours, remove the specimen and heat it with a hairdryer. Simultaneously, use foam to absorb excess polyethylene glycol from the surface. Shape it immediately before it cools. If the internal organs shrink after plastination, they can be filled with paraffin wax. The specific procedure is as follows: place the plastinated specimen in a 60°C incubator, use a syringe to draw molten paraffin wax (must be molten above 60°C), and inject it into the shrunken areas of the specimen to fill them completely.

 

 

Animal viscera specimens obtained through the above plastination method are well-shaped, relatively flexible, and have a certain degree of elasticity. They have a glossy appearance, and the color and texture meet teaching requirements.