Cell culture is the process by which cells are grown under controlled conditions, usually outside their natural environment. Once the cells have been isolated from living tissue, they can then be maintained under controlled conditions. These conditions vary for each cell type, but usually consist of a suitable container with a substrate or medium that provides essential nutrients (amino acids, carbohydrates, vitamins, minerals, growth factors, hormones and gases, O2), and regulates the physico- chemical environment (pH buffer, osmotic pressure, temperature). Most cells require an artificial surface or substrate (adherent or monolayer culture) while others can be grown by floating freely in a culture medium. Most cells of the lifespan are genetically determined,
In practice, the term "cell culture" now refers to the culture of plant cells, fungal culture and microbiological culture. Historical development and cell culture methods are closely linked to those of tissue culture and organ culture. Viral culture is also linked to the presence of viruses of cells.