Which fixative is recommended for fixation and preservation of phospholipids in tissue due to the presence of calcium chloride?

• A. Calcium Formalin
• B. Formalin Alcohol
• C. Glutaraldehyde
• D. 10% NBF

Answer: (A)

Phospholipids are lipids that make up cell membranes, and they’re easily lost during routine fixation because many fixatives dissolve lipids or don’t protect the membrane well. Calcium chloride in the fixative provides calcium ions that help stabilize the phospholipid membrane, reducing extraction, while the formaldehyde portion crosslinks proteins and preserves cellular structure. This combination specifically aids in maintaining phospholipid integrity within tissue, so calcium formalin is the preferred choice when phospholipid preservation is a goal.

Formalin alone or fixatives with alcohol tend to extract lipids, compromising phospholipid preservation. Glutaraldehyde is a strong protein fixative but doesn’t include calcium to support lipid stability, and 10% neutral buffered formalin lacks the calcium component that helps retain phospholipids.