Certified Surgical Technologist (CST) Practice Exam

Which of the following is a commonly used preservative for tissue specimens?

1. Saline

2. Formalin

3. Ethyl alcohol

4. Lugol's solution

The correct answer is: Formalin

Formalin is a commonly used preservative for tissue specimens due to its effectiveness in maintaining cellular structure and preventing decay. It is a solution of formaldehyde in water, typically at a concentration of 10%, and is used extensively in histopathology to fix tissues before they are processed for microscopic examination. The formaldehyde cross-links proteins, thereby stabilizing tissues and making them less likely to decompose. Saline, while it may be used for rinsing or transporting tissues, does not have preservative qualities and cannot maintain the integrity of cells for extended periods. Ethyl alcohol is used in certain applications but is primarily employed for dehydrating tissues rather than preserving them in the same way formalin does. Lugol's solution, an iodine-based solution, is more commonly used for staining purposes and does not serve as a general-purpose preservative in tissue specimen handling. Therefore, formalin stands out as the appropriate choice in this context.