Question
Fri August 15, 2008 By: Anusha Sen

Regeneration and fragmentation

Expert Reply
Fri August 15, 2008

Fragmentation is only seen in multicellular organisms with a simple body organisation, On the other hand regeneration is observed in fully differentiated multicellular organisms. Another important point to remember is that Regeneration takes place with the help of certain specialized cells.

Renegeration is the growing back of a lost part of the body of an organism. It is also used as a method of defence. Fragmentation is the unintentional cutting up of the body of an organism which each grows into different organism.

Hydra can be cut into any number of pieces and each piece can grown into a complete organism.

When a hydra is bisected anywhere in the upper 7/8ths of the body column, the upper half will regenerate a foot at its basal end, and the lower half will regenerate a head at its apical end; each half generates the organ that it is missing. The regeneration is precise, the head and foot are always formed specifically at the apical and basal ends, respectively. The most dramatic form of regeneration in hydra is the ability to form complete animals from aggregates of cells.

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