The term 'Tissue culture' can be applied to any multicellular culture growing on a solid medium that consists of many cells in protoplasmic continuity. The culture of an explant, consisting of one or more tissue, results in a callus that has no structural or functional counterpart with any tissue of the normal plant body. The use of tissue culture methodologies for studies has a short but productive history in agronomy and horticulture. The very recent ...