Differentiation, Dedifferentiation and Redifferentiation

  •  Differentiation, Dedifferentiation and Redifferentiatio
  • Differentiation;: It refers to the permanent qualitative changes in structure, chemistry and physiology of cell wall and protoplasm of cells, tissues and organs. It occurs by the activation or repression of some genes. For example, to form a tracheary element, the cells would lose their protoplasm. They also develop a very strong, elastic, lignocellulosic secondary cell walls to carry water to long distances even under extreme tension.
  • Dedifferentiation: It is the process of despecialisation of differentiated living cells so that they regain the capacity to divide and form new cells. A dedifferentiated tissue can act as meristem, e.g., interfascicular vascular cambium, cork cambium and wound cambium. in culture experiments, parenchyma cells dedifferentiate to produce a mass of dividing cells called callus,
  • Redifferentiation: Structural, chemical and physiological specialisation of cells derived from dedifferentiated meristematic cells is called redifferentiation. It is similar to differentiation of cells and tissues formed by primary meristems. Secondary phloem, secondary xylem, cork and secondary cortex are some of the tissues formed through redifferentiation.
  • The same apical meristem cells give rise to different types of cells, e.g., xylem, phloem, parenchyma, sclerenchyma fibres, collenchyma, etc. The reason for the formation of different types of cells and tissues from the same type of meristematic cells is commitment or determination. It is generally due to location and reception of particular signals. For example, cells distal to root apical meristem form root cap, while on the periphery they form epiblema followed by cortex, endodermis, pericycle, vascular tissues, etc..
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