Which statement about primary cells in culture is true?

• A. Primary cells have limited growth but retain more in vivo characteristics
• B. Primary cells grow indefinitely
• C. Primary cells are less relevant for cytotoxicity
• D. Primary cells cannot be cultured

Answer: (A)

Primary cells are taken directly from tissue and cultured, and they have a finite lifespan with limited divisions. This restricted growth is paired with a closer resemblance to the tissue’s in vivo physiology—maintaining native gene expression, receptor patterns, and metabolic behavior. That combination makes them especially valuable for cytotoxicity testing of dental materials, because their responses better reflect what would happen in real tissues than immortalized cell lines. Immortal cell lines, which can grow indefinitely, often diverge from normal tissue behavior, and primary cells can indeed be cultured (though they don’t proliferate endlessly). So, the statement is true because it highlights the trade-off between limited proliferation and greater physiological relevance.