Excretory Organ of Planaria

Regeneration studies in Planaria

Tissue culture, nuclear transplanting, stem cell research, tissue response to hormones are all recent interesting experimental fields in biology. An application of such practices requires a basic knowledge of regular processes as such as cell divisions, cell organization, cell transformation, cell initiations, cell’s responsiveness, immune systems, cell differentiation, organ repairing and wound healing. These inquisitive studies have paved the way for applicability of biological knowledge towards human welfare. ‘Regeneration’ has remained as one such study, that could provide a wealth of knowledge regarding the behaviour of somatic cells in growth and differentiation. The animals possess the ability to repair extensive damages incurred by the body either accidentally or in natural conditions. The ability of a living organism to regrow a portion of its body that has been injured or lost is known as regeneration. The capacity to regenerate lost parts differs in various groups of animals.

Organisms like sponges and coelenterates have exceedingly high ability for regeneration. As the organization of animals becomes advanced the capacity for regeneration gets restricted. Crabs can replace severed legs. Mammals can regenerate blood cells. Other specialized cells are replaced with scar tissue that does not regain the function of the lost or damaged tissue. Among multicellular and triploblastic animals the Planarians are remarkable for their high regenerative ability. They may be cut across or lengthwise, and each part of the body will regenerate the missing half

Mechanism of regeneration The process of regeneration happens through epimorphosis and morphallaxis. When a cut is made, a regenerative blastema is formed, at the cut surface. This process is termed as epimorphosis. Later the remaining part gets reorganized on a  small scale resulting in a smaller regenerated organ. This reorganization is called as morphallaxis. The processes of regeneration are controlled by many factors. A knowledge of all factors and the mechanisms of regeneration even to-day remain as potential fields for further research, study and application.