ABSTRACT
Cultured cells are often used in experiments as a surrogate for animals, and/or to simplify the system being studied. Thus they give a researcher a model for the whole animal, which is easier to manipulate on many levels and is on the whole much cheaper. Cells that are derived from fresh tissues and grown in flasks essentially unchanged are called primary cultures. Many cell lines are derived from tumours that grow well in culture by virtue of the fact that they are already immortalised as part of the transformation process inherent in tumorigenesis. Transformed cells differ from immortalised cells in that they are not subject to contact inhibition, have reduced serum dependence, exhibit anchorage-independent growth and can produce tumours when injected into athymic (nude) mice. All cell lines are different, and will have different requirements in order for them to grow.
