Cell suspensions (see Chap. 4)Whereas in a callus culture there remain connections among adjacent cells viaplasmodesmata, ideally in a cell suspension all cells are isolated. Under practicalconditions, however, also in these cell populations there is usually a high percentageof cells occurring as multicellular aggregates. A supplement of enzymes is ableto break down the middle lamella connecting the cells in such clumps, or a mechanicalmaceration will yield single cells. Often, cell suspensions are produced bymechanical shearing of callus material in a stirred liquid medium. These cell suspensionsgenerally consist of a great variety of cell types (Fig. 1.2 ), and are lesshomogenous than callus cultures.