How regeneration occur in amphibians limbs? It's types. All four types.

1. Introduction
Khurram shahzad
Roll no : 876
Semester : 6
Dept : Zoology
Govt. College of science(Wahdat road)

2. Topic of presentation
Regeneration in invertebrates

3. Defination
Regeneration is the reactivation of develpment in
postembryonic life to restore missing tissues.

4. Methods of
Regeneration
1: stem cells mediated regeneration
2: Epimorphosis
3: morphallaxis
4: compensatory regeneration

5. 1. Stem cell mediated
Regeneration
• Stem cells allow an organism to regrow certain
organs or tissues that have been lost.
• Example :
• Regrowth of hair shafts from follicular stem cells in
the hair bulge .

6. Example:
Regrowth of hair shaft from
follicular stem cells in the hair
bulge

7. 2. Epimorphosis
• In some species, adult structures can undergo
dedifferentiation to form a relatively
undifferentiated mass of cells that then
differentiates to form the new structure.

8. Example
Such epimorphosis is
characteristic of planarian
flatworm regeneration and also
of regenerating amphibian limbs.

9. 3. Morphallaxis
Morphallaxis is the regeneration of specific tissue in a
variety of organisms due to loss or death of the
existing tissue. The word comes from the Greek
allazein, which means to change.

10. Example
Such regeneration is seen in
hydra (a cnidarian).

11. 4. Compensatory
regeneration.
Here, the differentiated cells divide but maintain their
differentiated functions. The new cells do not come from
stem cells, nor do they come from the dedifferentiation of
the adult cells. Each cell produces cells similar to itself; no
mass of undifferentiated tissue.

12. Example
This type of Regeneration is a
characteristic of mammalian liver
.

13. Explanation of
Regeneration in salamander

14. Epimorphic
Regeneration of
Salamander limb
The new cells construct only the
missing structures and no more
In some way salamander limbs
know where the proximal distal
axis has been severed and is able
to regenerate from that point on

15. 1: Regeneration
of blastema
Salamanders accomplish
epimorphic regeneration by cell
dedifferentiation to form a
regeneration blastema. It is an
aggregation of relatively
dedifferentiated cells derived
from the originally differentiated
tissue. This blastema then
proliferates and differentiates
into the new limb parts. Bone,
dermis, and cartilage just
beneath the site of amputation
contribute to the regeneration
blastema, as do satellite cells
from nearby muscles.

16. 2: Formation of
apical ectodermal
cap (ACE)
When a salamander limb is
amputated,a plasma clot
formswithin 6-12 hours
epidermal cells form the
remaining stump migrate to
cover the wound surface
,forming the wound epidermis.

18. 3