American Society for Clinical Pathology (ASCP) Histotechnologist Practice Test

Which component is NOT a function of acetic acid as a fixative?

1. Penetration of tissue

2. Preservation of carbohydrate structures

3. Softening of tissue

4. Fixation of cell nuclei

The correct answer is: Preservation of carbohydrate structures

Acetic acid serves several important functions as a fixative in histology, but preservation of carbohydrate structures is not one of its primary roles. Acetic acid is primarily used for its properties in fixing tissue and softening it to allow for better penetration of other fixatives and dyes. It helps in the penetration of tissue by decreasing tissue rigidity, which enhances the ability of other fixatives to access cellular components. In the context of softening tissue, acetic acid contributes to the process by altering the proteins and making the tissue more amenable to further treatment and embedding. The fixation of cell nuclei, particularly through its action that leads to nuclear protein coagulation, is also a notable role of acetic acid. However, regarding carbohydrate preservation, acetic acid does not stabilize carbohydrate structures effectively. Other fixatives, such as formaldehyde, are better suited for this task as they promote the integrity of glycoproteins and polysaccharides. Thus, the assertion that preserving carbohydrate structures is a function of acetic acid stands in contrast to its actual behavior, affirming that it is not a function of acetic acid as a fixative.