Dedifferentiation
மீள் வேறுபாடு
Biology is not static. A cell that has matured and stopped dividing can reverse its fate. This is not magic; it is dedifferentiation, and ignoring this mechanism will cost you marks in the Plant Growth and Development section.
The idea
Dedifferentiation is the process where living differentiated cells, which have lost the capacity to divide, regain the ability to divide under specific conditions. This allows the formation of meristems, such as interfascicular cambium and cork cambium, from fully differentiated parenchyma cells. It is a fundamental reversal of the maturation process.
Why it matters
This allows plants to heal wounds and form secondary meristems like cork cambium, enabling secondary growth and repair mechanisms.
NEET lens
NEET focuses on the origin of secondary meristems. Memorize that interfascicular cambium and cork cambium are products of dedifferentiation. Do not confuse this with 'redifferentiation', where these cells mature again to form secondary xylem and phloem.
Clinical significance
In humans, the loss of control over dedifferentiation leads to neoplasia. When cells revert to a proliferative state without regulatory signals, they form tumors. Cancer is essentially the pathological, uncontrolled dedifferentiation of somatic cells.
Introduction
Dedifferentiation is the process by which a differentiated cell loses its specialized characteristics and reverts to a more meristematic (stem-cell-like) state, capable of dividing again.
Core concept
Occurs in plants: Wound healing — parenchyma cells near wounds dedifferentiate → form wound callus (undifferentiated cell mass). Tissue culture — explant cells dedifferentiate in response to auxin/cytokinin in media → form callus. Natural examples: vascular cambium formation — interfascicular parenchyma dedifferentiates → becomes cambium (secondary growth initiation). Cork cambium (phellogen) formation from parenchyma or epidermis after wounding. Prerequisite for regeneration in plants.
Go deeper
Dedifferentiation mechanism: wound signals (auxin, cytokinin, sugars) activate cell cycle re-entry. Epigenetic marks of differentiation are erased → genes for division expressed again. This is essentially reverse of differentiation — chromatin remodeling resets gene expression patterns.
From Class 10
Usually cells go from stem cells → specialized cells. But some differentiated cells can reverse direction and become less specialized again. This reversal is dedifferentiation.