Tissue Regeneration

Tissue Regeneration

Write in briefly about tissue regeneration.
Answer:

Regeneration

When healing takes place by the proliferation of parenchymal cells and usually results in the restoration of original tissues.

• In order to maintain the proper structure of tissues, cells are under constant regulatory parenchymal control of their cell cycle.
• Cell cycle is defined as the period between two successive cell divisions and is divided into unequal phases.
• G1 (Pre-Mitotic Gap) Phase: It is the stage when mRNA for proteins and proteins themselves required for DNA synthesis are synthesized.
• S Phase: During this phase synthesis of nuclear DNA takes place.

• G2 Phase: It is the short gap phase in which the correctness of DNA synthesized is assessed.
• M Phase: It is the stage in which process of mitosis to form two daughter cells is completed, this occurs in four sequential stages, i.e. prophase, metaphase, anaphase and telophase.
  • Prophase:
    • Each chromosome divides into two chromatids which are held together by a centromere.
    • The centriole divides and two daughter centrioles form the spindle, while the chromosomes line up at the equatorial plate of the spindle.
  • Anaphase:
    • The centromeres divide and each set of separated chromosomes moves towards the opposite poles of the spindle.
    • Cell membrane also begins to divide.
      • Telophase:
        • There is the formation of a nuclear membrane around each set of chromosomes and the reconstitution of the nucleus.
        • The cytoplasm of the two daughter cells completely separates.
      • Go Phase: The daughter cells may continue to remain in the cell cycle and divide further or may go out of the cell cycle into the resting phase called as G0 phase.

Tissue regeneration

Regeneration of parenchymal cells involves the following two processes:

• The proliferation of original cells from the margin of injury with migration so as to cover the gap.
• The proliferation of migrated cells with subsequent differentiation and maturation so as to reconstitute the original tissue.