Question

Which of the following is not a fixative?

• A. 10% Formalin
• B. 5% Nitric Acid
• C. Bouins fluid
• D. Carnoys fluid

Answer 1

Answer:

B. 5% Nitric Acid

• In histology and microscopy, a fixative is a chemical agent used to preserve biological tissues from decay, due to autolysis or putrefaction.
• Formalin (a solution of formaldehyde in water) is the most common fixative used in laboratory settings.
• Alcohol (specifically ethanol) acts as a coagulating fixative by precipitating proteins.
• Glutaraldehyde is widely utilized as a fixative for electron microscopy because it preserves ultrastructural details effectively.
• Acetone is often used in combination with other fixatives or for specific immunohistochemical staining procedures.
• Potassium permanganate is an oxidizing agent and is typically used as a stain or an oxidizer in laboratory protocols, not as a standard tissue fixative.
• Other common fixatives include Bouin's solution, Paraformaldehyde, and Osmium tetroxide.