Modern plant tissue culture is practiced underrnaseptic or favourable conditions under filtered air. Living plant materialsrnwhich was taken from the environment or free space are being naturallyrncontaminated or will show contamination on their external surfaces (andrnsometimes interiors) with pathogenic microorganisms, so surface sterilization ofrninitial materials (explants) in chemical solutions (usually Sodium or calciumrnhypochlorite or mercuric chloride) is done. Mercuric chloride isrnmostly used as a plant sterilant now a days, unless other sterilizing agentsrnwhich require for removal of contamination are dispose found to be leastrneffective, as it is very dangerous and harmful to use, and is very difficult torndispose of. Explants are then generally placed or maintained on the upperrnsurface of a solidified culture medium (normally MS) but during some cases itrnwill be inoculate directly into a liquid nutrient medium, normally when cellrnsuspension cultures are required. Solid nutrient and liquid nutrient mediarnusually consists of hormones. Solidified media are prepared orrnproduced from the liquid media with the use of a gelling or solidified agent,rngenerally a purified agar. The constituents of the solid medium or thernrequirement of the plant growth hormones and the nitrogenous sourcern(nitrate/ammonium salts and amino acids) have produces morphological effects ofrnthe grown tissues that from the initial explants. For example, highrnconcentration of auxin responsible for the high multiplication of roots whereasrnan excess cytokinin may yield shoots. A balance concentration of auxin andrncytokinin will often generate an unorganised and undifferentiated growth ofrncells, i.e. callus, but the morphology of the outgrowth depends on therndifferent plant varieties as well as the suitable medium composition.