Callus and Suspension Cultures - When explants are cultured on a suitable GR combination, many of its cells undergo division. Even mature and certain differentiated: e.g., parenchyma and often colenchyma, cells undergo changes to become meristematic; this is called dedifferentiation. Dedifferentiation involves, among other things, renewed and enhanced RNA and protein syntheses leading to the formation of new cellular components needed for meristematic activity. Initially, cell division is confined to the cut ends, but subsequently it covers the entire explant. The resulting cell mass is ordinarily unorganised, but it often consists of several cell types including fibers, and vascular elements.