Regeneration - Development Biology

Regeneration has, intrigued scientists for several generations and has resulting in voluminous literature on the subject beginning from the eighteenth century. T. H. Morgan 1901 has been primarily accountable for formulating the principles which form the basis of the recent studies of regeneration. The main problems of regeneration identified by Morgan are being investigated even to this day. These include the origin and developmental potential of cells that are accountable for the production of the regenerate, the role of the adjacent tissues in ascertaining the structure of the regenerated limb and the reasons for the enormous variation in the regenerative capabilities of various animals. What does regeneration mean in biological terms? Regeneration is a fascinating phenomenon. It includes continuity of the developmental processes or reawaking of the process of morphogenesis and differentiation in post-embryonic life in an already made and functional organism.

Regeneration takes place at various level of organization. At the sub-cellular and molecular level it is manifested in the continuous synthesis to replenish used up substances in the cells. At the sub-cellular and tissue levels it includes replacement of worn out cells, repair of damaged tissues and healing of wounds. At these levels the ability to again generate is a universal characteristic of all animals without which life of any individual would be impossible. At the organismic level regeneration contains de novo (afresh) development to restore the lost part of an organ or the reconstitution of the complete body from the residual pan of the organ concerned. This includes retracing many of the complex steps of the original ontogenetic development in a functional body within quite different physiological and environmental conditions. The capacity for this sort of regeneration is referred to as reparative or restitutive regeneration and is not evenly distributed in the animal kingdom. A few have great powers to restore lost parts, or even to form a whole body from a small piece. Others have variously restricted and limited abilities of such as regeneration, and still others have no power of reparative regeneration at all. The reasons for such type of inequality of regenerative power among animals are not clear.

In many groups, the animals show the phenomenon of autonomy, by which they themselves cast off or lose one or much more parts of the body when disturbed or threatened by an enemy or a predator. The autotomized (self-amputated) parts are consequently regenerated. Different animals employ varied method for the regeneration of lost parts. The study and investigation of the phenomena of regeneration are of great help in the efforts to understand the basic procedures and mechanisms of development as such.