Cell culture techniques were developed as a way to study animal cells in vitro. The behavior of single cells, organ culture and monolayer cells can be studied without the in vivo influences arising from physiological and environmental variations among experimental animals. Cell culture or tissue culture as the technique is widely known, was first described in 1907 (Freshney 1987) and through the decades has undergone extensive developments. These include the introduction of defined media, the development of continuous cell lines, cell fusion techniques and the extension of animal cell culture techniques to plant, insect and lower vertebrate cell culture.