Primary culture refers to the initial growth of microorganisms or cells in a controlled environment, typically in a laboratory setting. This process involves isolating cells from a tissue sample or organism and placing them in a nutrient-rich medium that supports their growth. Primary cultures are essential for studying cellular behavior, disease mechanisms, and drug responses. In biological research, primary cultures are often used to investigate specific cell types, such as neurons or hepatocytes. Unlike cell lines, which are derived from primary cultures and can be maintained indefinitely, primary cultures have a limited lifespan and closely resemble the original tissue, making them valuable for accurate experimental results.