Epimorphosis

Introduction

Regeneration refers to the process of growth, repair and restoration of damaged tissues and organs and epimorphosis is one of the processes of regeneration in an organism.

What is Epimorphosis?

Epimorphosis is the process of regeneration of a specific tissue or organ that is achieved through cell proliferation, dedifferentiation and reformation. It can also involve the formation of the blastema.

Epimorphosis is a simple development model in which the development occurs at the site of injury of the tissue or organ and not the whole organism. It helps restore the organism's anatomical structure and restores the original polarity that existed before the structure was destroyed.

Epimorphosis is also known as Epimorphic regeneration is seen in vertebrates and invertebrates. Some organisms in which epimorphosis can is witnessed are salamanders, annelids and planarians.

In this tutorial, we will be looking at epimorphosis in vertebrates as well as invertebrates, important terms related to epimorphosis.

Epimorphosis in Vertebrates

In vertebrates, the process of epimorphosis is initiated by blastema formation which then results in the proliferation of cells into tissues.

The best example of epimorphosis in vertebrates can be the regeneration of limbs in salamanders.

Process of Epimorphosis in Salamander

• In the first step, the epidermal cells located near the region of the wound migrate to the wounded area and cover it. Mesenchymal tissues present in the limb secrete MMP which thickens the wound tissue and forms the stump tip.

• The nerves present in the location of injury get degraded which results in re-establishment that involves dedifferentiation of cells.

• The release of fibroblast growth factor from the apical ectodermal cap (formed by thickening of wound tissue) helps in setting the limbs to their state of embryonic development.

• During the process of regeneration, the specialised cells will be differentiated into the specialised tissue (e.g. cartilage cells can form new cartilage cells).

• The distal part of the limb interacts with the original part to form the intermediate limb in a process called incarnation.

• A new limb is formed after all the process is completed.

Epimorphosis in Invertebrates

The process of epimorphosis in invertebrates occurs due to the formation of blastema that differentiates into new tissues and due to the presence of pluripotent stem cells. These new cells can develop into the new organs that are needed for the organism.

Examples of epimorphosis in invertebrates are the regeneration of the tail in lizards and the regeneration of limbs of the American cockroach. Another well-known example is that of the flatworm Planaria, in which the whole organism can regenerate from a single piece.

Important Terms related to Epimorphosis

• Blastema − Blastema is referred to as a group of undifferentiated cells that has the ability to develop into new tissue or organ. It is an essential component of the regeneration process.

• Dedifferentiation − Dedifferentiation is a process in which the cells lose their special function and revert to their early development stage. The cells can perform a variety of functions which is especially common during the regeneration process.

Conclusion

Epimorphosis is a type of regeneration process found in both vertebrates and invertebrates. The regeneration of limbs in salamander and regeneration of planaria are examples of epimorphosis.

FAQs

Qns .1 What is an example of epimorphosis in vertebrates?

Ans. The regeneration of the limb of a salamander is an example of epimorphosis in vertebrates.

Qns .2 What are examples of invertebrate epimorphosis?

Ans. The regeneration of planaria (flatworms) and reptiles (like lizards).

Q.3 What is dedifferentiation?

Ans. Dedifferentiation is the process in which a cell loses its special function and reverts to its developmental stage. Here the cells can perform different functions.

Qns .4 What is blastema?

Ans. Blastema refers to the mass of undifferentiated cells which possess the capability of developing into new organs or body parts.