Introduction
One of the earliest workers in cell and tissue culture was Harrison who in 1907 developed a reproducible technique for tissue culture using frog. Later in 1912, Carrel used tissue embryo extracts as culture media. They successfully demonstrated that animal cells can be grown indefinitely in vitro just like other microorganisms. Initially cold-blooded animals like frog were used, so that no incubation was required, but later warm-blooded animals like chick and rodents were used and eventually mammals became a favourite material.

Culture Media
Culture medium is the single most important factor for culturing cells and tissues. It provides the optimum conditions of factors like pH, osmotic pressure, etc., and the chemical constituents, which the cells or tissue are incapable of synthesizing (unlike microorganisms, which can synthesize them from simple inorganic substances). Animal cells need either a completely natural medium or an artificial medium supplemented with some natural products. For some tissues, the natural medium is preferred, since it is the cheapest and most convenient.