What is Morphallaxis Definition Process and Examples
The process through which organisms experience regrowth and renewal is called morphallaxis. Not all animals regenerate in the same manner; hydra and jellyfish replace their missing parts by reorganising from the pre-existent ones. This process occurs in plants, animals, and humans also. In humans, regeneration of the liver is the best example and in animals, it occurs in lizards. Hydra is the best example for plants where budding happens from dissociated cells.
Defining Morphallaxis
Morphallaxis is the regeneration by transformation, renewal, and rebirth of existing body tissues. It is a biological process of reorganising the leftover parts in vertebrates into new organisms. It depends on the remodelling and reconstruction of already existing body tissues. If we observe one severed section of the hydra, they form smaller versions of the original hydra, thus facilitating an exchange of tissue and forming two fully functional and independent hydra.
Morphallaxis Regeneration
There is a slightly different process from morphallaxis known as epimorphosis. In morphallaxis, regeneration happens from reorganisation, whereas in epimorphosis, regeneration occurs from cellular differentiation. An example of morphallaxis is budding in hydra, whereas epimorphosis is when a lizard repairs its cut-off tail.
Morphallaxis is observed in many lower animals and occurs as a result of an injury, bisection of an animal, etc. Researchers Wison and Child proved in 1930 that hydra was pulped and put in an aqueous solution. Even then, it would shortly reform into a new hydra. This regeneration is morphallactic. If our finger is cut off, we cannot restore it, but hydra, if cut into a few pieces, will regenerate to form new individuals. There is an exception, though in planarians, as in some vertebrates such as salamanders, regeneration through cell proliferation and morphallaxis are both needed for complete renewal.
Regeneration also is of two types, that is, reparative and restorative. Our livers are a prime example of regeneration, but here they make new cells which are called hepatocytes, which actually work like stem cells.
Morphallaxis Examples
An example of morphallaxis is ‘budding in hydra’, which is the process where a new hydra grows from its parent body. When a hydra is cut into half, the upper part develops a foot, and the lower part develops a head.
Regeneration happens in two ways:
In morphallaxis, any organism that is cut is regenerated into a complete organism; for example, planaria and hydra can regenerate into whole organisms,
In epimorphosis, the injured part is repaired. For example, a lizard repairs its cut tail. In this process, some undifferentiated cells known as 'blastema ' are formed, and they rapidly divide to form a new tail.
The regeneration of skin and liver is the prime example of regeneration in humans. Regeneration also happens in planarian flatworms and limbs of amphibians. Other examples are salamanders, annelids, etc.
Morphallaxis Hydra
Hydra belongs to a group of freshwater Cnidarians that are 0.5 cm in length; they possess a short tubular body. The head part of hydra contains the mouth and tentacles, the lower part has the head. It is one of the few organisms that have great regeneration calibre. This peculiar property has made this genus one of the most important models for understanding the process of regeneration. They can regenerate missing parts upon transverse and longitudinal amputation.
The whole hydra body forms within 4 to 7 days after amputation. Immediately after amputation, there is a reorganising of epithelial cells to close the wound, the emergence of tentacles emerge within the next 24 hours, and the whole process takes place within 72 hours. Major cell reorganisation happens over the next few days, thus completing the process in 4 to 7 days.
Interesting Facts
An Interesting fact is that salamanders can regrow their damaged hearts, too, along with limbs, jaws, retina, etc.
If in hydra any amputation happens away from the mid-gastric region, it will exhibit morphallaxis mode, but if amputation is done after head generation and mid-gastric cut, then it proceeds through the process of epimorphosis.
Important Questions
1. What is the mechanism behind morphallaxis?
Ans. The mechanism involved in morphallaxis is regenerative tissue remodelling. Scientists have long since been amazed at the ability of planarian flatworms to regenerate their parts of their bodies in a few days. The mechanism includes repatterning, proportioning and studying the rate of cell death.
2. What is the process of blastema?
Ans. Amphibians can regenerate their limbs by forming their limbs throughout their lives. The blastema forms a thickening of epidermis closing the wound. Blastema cells are derived by cells from tissues by histolysis and dedifferentiation and also through stem cells from the muscle.
Key Features of Morphallaxis
There are various environmental factors affecting morphallaxis. They are internal and external, like temperature, pH, excretory substances, etc.
Morphallaxis is observed in many lower animals and occurs as a result of an injury, bisection of an animal, etc.
Hydra can unravel several facets of their role in physiological regeneration in a much more complex system such as humans.
Hydra is the best example for plants where budding happens even from dissociated cells.
FAQs on Morphallaxis in Regeneration Biology
1. What is morphallaxis in biology?
Morphallaxis is a type of regeneration in which an organism reforms missing parts mainly by reorganizing existing cells rather than by producing many new cells. In morphallaxis:
- Existing tissues are rearranged and re-patterned.
- There is little or no cell proliferation.
- The regenerated structure is often smaller but proportionally correct.
2. How does morphallaxis occur?
Morphallaxis occurs through the reorganization of pre-existing cells to restore lost body parts. The process involves:
- Wound healing after injury.
- Repatterning of existing tissues.
- Cellular redifferentiation without significant mitosis.
3. What is the difference between morphallaxis and epimorphosis?
The main difference is that morphallaxis involves tissue reorganization with minimal cell division, while epimorphosis involves active cell proliferation and formation of a blastema. Key differences include:
- Morphallaxis: Reorganization of existing cells; little growth.
- Epimorphosis: Formation of a blastema and extensive mitosis.
- Example: Hydra (morphallaxis) vs. salamander limb regeneration (epimorphosis).
4. Which organisms show morphallaxis?
Morphallaxis is mainly seen in simple multicellular organisms such as Hydra and some cnidarians. Examples include:
- Hydra regenerating a whole body from a fragment.
- Certain flatworms showing partial morphallactic regeneration.
5. Is morphallaxis a type of regeneration?
Yes, morphallaxis is a type of regeneration in which lost body parts are restored by remodeling existing tissues. It differs from other regeneration types because:
- It involves minimal new tissue growth.
- The body axis may be re-established.
- The regenerated organism may initially be smaller in size.
6. Does morphallaxis involve cell division?
Morphallaxis involves little or no cell division compared to other regenerative processes. Instead:
- Existing cells change position and function.
- Cells undergo redifferentiation.
- Tissue patterning is restored without forming a blastema.
7. What is an example of morphallaxis in Hydra?
In Hydra, morphallaxis occurs when a small body fragment reorganizes to form a complete miniature individual. For example:
- If Hydra is cut into pieces, each piece can regenerate missing parts.
- The cells rearrange to re-establish the oral and aboral ends.
- The new Hydra is proportionally correct but initially smaller.
8. Why is morphallaxis important in biology?
Morphallaxis is important because it demonstrates the ability of cells to reorganize and change function during regeneration. Its significance includes:
- Understanding cellular plasticity.
- Insights into body pattern formation.
- Applications in regenerative biology research.
9. How is body pattern restored during morphallaxis?
During morphallaxis, body pattern is restored through tissue remodeling and positional information among cells. The process includes:
- Re-establishment of the body axis.
- Cell signaling between neighboring cells.
- Re-specification of cell fate.
10. Can humans undergo morphallaxis?
Humans cannot undergo true morphallaxis because they lack the extensive tissue reorganization ability seen in simple organisms. In humans:
- Regeneration is limited (e.g., liver regeneration).
- Healing mainly involves scar formation.
- There is no whole-body re-patterning mechanism.
