Calcium Formalin is recommended for the fixation and preservation of which tissue component?

• A. Phospholipids
• B. Nucleic acids
• C. Proteins
• D. Carbohydrates

Answer: (A)

Calcium formalin is preferred when the goal is to preserve phospholipids, the lipid components of cell membranes. The calcium ions help stabilize lipid structures and reduce the loss or solubilization of phospholipids during fixation, so membrane lipids stay intact more reliably than with formalin alone. This makes it especially suited for preserving phospholipid-rich components of tissues. Nucleic acids are more affected by crosslinking and generally require other methods to preserve well; proteins fix well with formaldehyde, while carbohydrates are best preserved with different fixatives or special stains.