Regeration

1. REGENERATION

2. CONTENTS
 Introduction
 Regeneration ability in invertebrates
 Regeneration ability in vertebrate
 Types of Regeneration
 Mechanism of Regeneration
 Factors influencing Regeneration

3. Introduction -:-
 It is post-Embryonic morphogenic
phenomenon,which when temprorily stimulated
brings about repair of damaged cell/tissue,
replacement or redevelopment of several body
parts or whole body from small body fragments.
 Among animals the power of
Regeneration was first discovered in Hydra
by Abraham Trembley in (1744).
Defination:-

4. Types of Regeneration
Regeneration mainly of two types- Reparative and
Restorative
1)Reparative regeneration: In this, multicellular
organism has the power to repair certain damages
cells of the body. It is a common phenomenon
observed in both invertebrates as well as the
vertebrates.
e.g: Hydra
2)Restorative regenerations: In this multicellular
organism can develops the several body parts or the
whole body.
e.q. Star fish, Lizards

5. Mechanism of Regeneration
*Epimorphic Regeneration –when a body part is repaired due to
addition of the parts to the remaining pieces of that parts. It replaced lost
part of body by proliferating new cells fron the surface of injured parts
Ex. Amphibian limb, lizards tail, arm of star fish.
*Morphallaxis Regeneration – It involving a re-organization of the
reaming part of the body of an animal. Reconstruction of entire body
from small fragments.
Ex. Hydra
*Heteromorphosis Regeneration – when a different organ develops
from the one that has been removed the phenomenon is called as
heteromorphosis Ex. Shrimp palinurus
*Super Regeneration – after the loss of complete limb or tail , results in
form of an additional limb Ex. Earthworm.

6. In-Invertibrates
 Protozoa - Regeneration occurs in most of protozoa but it
is more common in some species like Amoeba & ciliates.
 Porifera - If Sponges is cut into several pieces,any piece
can grow into a complete sponges because the very high
Regeneration power in sponges.

7. In Coelenterates :-
 Hydra being a lower animal shows Regeneration to an amazing
degree.
 If Hydra cut into two parts,each part grows into a new &
complete individual of diminished size.
 Hydra shows polarity of anterior-posterior differentiation in
Regeneration.
 Polarity is the fact that the anterior side of any section of the
animal grows head while the posterior side of the section grows
a tail.

8. In Platyhelminthes
 Among Platyhelminthes posses a unique power
of Regeneration, Planarians power of Regeneration
is maximum near head & minimum near the
posterior end .
 A planarians can regenerate the entire organism
from a middle section with the pharynx .

9.  In Annelids- Earthworm is cut into two halves, each may
regenerate onto the lost parts.
 In Arthropod - In arthropod, Regeneration is restricted to
the renewal of last appendages. Insects , spiders, crabs.
After loss of amputation of an appendage in an arthropod
wound is covered by chitinous cap.
 In Mollusca - The Regeneration is relatively poor in
mollusca, cephalopods may regenerates either arms only.
 In Echinoderms -The starfish,brittle stars & sea lilies can
regenerate arms & parts of the disc .

10. In - Vertebrates
Among the vertebrates the regeneration power is most spectacular in
the urodele amphibians , In salamander specially in their larva limb
as well as external gills also regenerate
1) In Fish- Regeneration is restricted only to fins.
2) In Amphibian –
Anurans –Regeneration takes place during larval stage only , when legs
first appear on a frog tadpole , they can be regenerated easily if lost .
Urodeles -In salamander limbs as well as tail can regenerate.
3) In Reptiles-
If lizard tail is lost, then regenerative blastema is formed on wound
surface & they give rise to tail.

11. In Mammals :-
Mammals cannot regenerate entire organ, they can howev regenerate
tissue.
Regeneration capacity is very poor, only beak can regenerte.
In birds :-

12. Regeneration of limb in
salamander
Mechanism of limb Regeneration
*Phase of wound healing
*Blastema formation
*Morphogenesis & differentiation

14. Role of genes in Regeneration
 Genes that are expressed in differentiated
tissue ( such as mrf4 & myf5 ) are down
regulated , while there is dramatic increase
in expression of genes such as msx1 that
are associated with proliferating progress.
 Dedifferentiated cell mass is the
regeneration blastema , these cell will
continue to proliferate & will eventually re-
dedifferentiated to form the new structure of
the limb .

15. Factors Influencing Regeneration:-
*Temperature :- The rate of Regeneration is
dependent on temperature increase of temperature up
to a certain point enhance regeneration.
*Food :- Regeneration is not much affected by food.
*Age :- The power of Regeneration usually diminished
with increasing age
.
*X-rays :- X-ray are found to retard or stop the process
of regeneration because they are known to inhibit or
suppress the mitotic activity of cells.