Which of the following describes primary cell culture?

Primary cell culture refers to the process wherein cells are directly isolated from living tissues and subsequently grown in vitro (in a controlled environment outside of their natural habitat). This method preserves the original cellular characteristics and functions of the cells, making them valuable for various biological and medical research applications.

The essence of primary cell culture lies in its connection to the source tissue, allowing researchers to study cells that retain many of the properties of the in vivo environment. These cells typically have a limited lifespan and will eventually undergo senescence, which differentiates them from other cell culture types, such as immortalized cell lines that can proliferate indefinitely.

In contrast, the other options describe different types of cell handling or culture methods. Cells grown indefinitely in artificial conditions refer to immortalized cell lines. Genetically modified cells indicate a manipulation that was not a part of the original cell isolation from tissue. Therefore, acknowledging primary cell culture as cells taken directly from living tissue captures the specific nature of this type of cell culture accurately.