Regeneration: Types, Regeneration in Plants & Hydra

Regeneration is a biological process that undergoes renewal, restoration, and tissue growth. As a result of the process, genomes, organisms, and ecosystems become resilient to natural fluctuations that cause disturbance or damage.

• Regeneration is a process in which organisms restore or replace amputated parts of their body.
• The process is either complete or incomplete.
• Organisms reproduce in order to pass their genetic information to the next generation. 
• Organisms can be broadly classified into simple organisms and complex organisms. 

Reproduction is a complex process that is elaborate and complicated due to the obvious reasons: larger body size, a greater number of cells, the presence of different kinds of cells, and sophisticated collection of cells into tissue, organs, and organ systems.

• The process of regeneration is carried out by specialized called stem cells.
• Each cell undergoes various changes, which is known as development.

Key Terms: Regeneration, Types of Regeneration, Morphallaxis, Epimorphosis, Regeneration in Plants, Regeneration in Hydra, Reproduction, Cells, Tissues, Genomes, Stem Cells, Organisms

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What is Regeneration?

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Simply put, regeneration is a method in which an organism, with the help of special cells, breaks up into parts, and each part further gives rise to individual organisms.

• In regeneration, the organism does not suddenly form a new organism.
• Instead, the specialized cells form a mass of cells that further undergo changes to become various types of cells.
• This process occurs in an organized, sequential manner is known as differentiation.
• The development of cells of organisms results in the formation of different body parts and organs.

Regeneration

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Types of Regeneration

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The two types of regenerative method known to occur in organisms are:

Morphallaxis

Morphallaxis is a type of regeneration where organisms undergo little growth. It depends upon the process of tissue repatterning. Consider the case of a hydra, which grows by the loss of cells by the process of budding.

• When it is divided into two halves, the upper part fill turns into the foot.
• The lower part of the body is converted into the head.

Epimorphosis

Epimorphosis is a type of regeneration where growth depends on a patterned structure. Consider the case of vertebrate limb, which involves dedifferentiation and growth of cells.

• The epidermal cells of the organisms result in the formation of blastema. 
• This will give rise to structures with positional distal values.
• The proximal-distal values in limb regeneration are changed by retinoic acid.
• It is also known as Restorative Regeneration.
• This process is frequently seen in lizards to grow a tail.
• Similarly, Starfish and Crabs also use epimorphosis to grow back a lost organ.
• It is observed in the tail of a lizard.

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Which Organisms can Regenerate?

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Regeneration is a biological process where an organism is restored to its original state after being divided into multiple parts. The process is carried out by specialized cells known as stem cells.

• The process is mainly carried out in organisms like hydra, flatworms, and tapeworms. 
• These organisms have unique regenerative capabilities. 

When these organisms are injured, their body cells get activated and work on repairing damaged cells. The process is more common among metazoans.

• Animals like crayfish, starfish and amphibians also undergo tissue regeneration. 
• The process of regeneration varies from organism to organism.
• Some organisms carry the process through stem cells, while some organisms do not require stem cells.

Can Humans Regenerate?

Yes, humans undergo the process of regeneration. In humans, the skin undergoes continuous regeneration even after getting injured. The liver also undergoes the process after the liver gets damaged due to disease and accidents. 

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Regeneration in Plants

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Like organisms, plants also have the capability to regenerate using precursor cells. The process of regeneration is usually carried out when plants get repaired or replaced based on the totipotency and pluripotency of their cells.

• Plants use the concept of tissue culture to regenerate.
• The process can be carried out by organogenesis and somatic embryogenesis.

Some trees are cut from the bottom, after which new roots will later emerge from the stump and develop into new leaves, flowers, and stems.

• Plants can be developed in the laboratory by the process of callus differentiation.

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Regeneration in Hydra

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Hydra is considered an important organisms that possess tremendous regeneration potential. It is capable of producing new organisms from small tissue fragments or even from dissociated cells. 

• Their cells are wounded to initiate the process of regeneration.
• The cells undergo morphallaxis, where the process results from the remodelling of existing material without cellular proliferation.
• It involves the exchange and rearrangement of soft tissues without the formation of new material.
• The process undergoes chromatin and gene expression regulation changes.
• Regeneration process in Hydra is as follows:

Hydra grows by continuously losing cells from its base and by budding

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A gradient of inhibitor is produced by the head. This prevents the formation of other heads

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The concentration of inhibitor is reduced

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The positional value increases locally

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A new head is formed without any new growth

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Things to Remember

• Regeneration refers to a biological process where the organism is cut into pieces, and each of its parts regrows to its original state.
• Morphallaxis and Epimorphosis are two of its types.
• Humans also have the ability to regenerate.
• In this, various processes like cell proliferation, morphogenesis and cell differentiation are initiated.
• The preparation phase and the redevelopment phase are two phases of regeneration.

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