Tissue Culture
It is an important technique for maintaining a'pm or piece of animal or plant tissue alive after their culture dishes. It is necessary to provide an environment in which cells can live and mulaiply over a periOd of time. Therefore. different media containing mixture of salts, amino acids, vitamins, Wwth factm etc. are used for this purpose. There art some special typeg of cul- media such as Balanced Sak Solution (BSS), and Essential Minimal Medium (EMM).
Cultures prepared directly from the tissue o{ an organism arc called prlmuy cultures. For obtaining the primary cultures, the organ is removed in a sterile atmosphere so as SO make it free from bacteria and other foreign bodies. Then it is cut into small pieces and treated with trypsin. Trypsin has the property of dissociating cell aggregates into a suspension of single cells, with affecting their viability. Cultures prepared frorn cells which were removed from primary cultures form sc~odalryc ultures. Such cells show che properties of the parent body frorn which they were obtained, for example, fibrbblasts secrete collagens; cells derived from embryonic skeletal muscle form muscle fibres. These phenomena which otherwise cannot be studied in intact tissues are easily studied by this technique.
Some cells show prolonged growth and di~ide~indefinjteilny vitro. These cells are called 'variant cells'. Such cells grow or propagate in a'linear Order indefinitely to form a cell line. Some commonly used cell lines are BHK 21 and Human HeLa cells which are derived from fibroblast of a hamster and epithelial cells of man respectively.
Many of these cell lines were derived from tumor like growth. All these cells are capable of dividing indefinitely in tissue culture and they express at least some of the properties which are different from the cell of origin. BHK 21 cells, and HeLa cells. are capable bf growing in suspension whereas other cell lines requin a solid culture substratum for their growth.
Unlike variant cells, cancer cells divide indefinitely in vivo (within the living organism) as well as in vitro (in the experimental conditions). They grow rapidly compared to normal . cells in a tissue culture dish. Tissue culture is an important technique which is used to study the fundamental problems in cell biology. One of the major advancements in tissue culture is cloning. A clone is a population of cells derived from a single parent cell.