Regeneration is the sequence of morphogenetic events that

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Regeneration is the sequence of morphogenetic events that restores the normal structure of an

Regeneration is the sequence of morphogenetic events that restores the normal structure of an organ after its partial or total amputation. Regeneration in invertebrates: • Hydra: Cross amputation of hydra led every part to regenerate to whole hydra species. • Planaria: The planaria contains neoblast cells which migrate toward the amputated region and form the lossing parts. • Annelids : The blastema of the amputated region formed of ectoderm , mesoderm and neoblast cells which co-ordinated in regeneration of the lossing parts.

Regeneration of vertebrates There are two types of regeneration: 1. Epimorphosis or epimorphic regeneration

Regeneration of vertebrates There are two types of regeneration: 1. Epimorphosis or epimorphic regeneration : This type of regeneration involve the reconstruction of the missing parts by local proliferation from the blastema, or addition of parts to remaining piece. For example: regeneration of tail, limbs and lens in anurans and urodels and other vertebrates. 2. Morpholaxis or morphollactic regeneration: This type of regeneration involving reorganization of the remaining part of the body of an animal. For example: Hydra, planaria and other invertebrates e. g. regeneration of the new individual from body pieces.

Regeneration Types of Regeneration: 1. Stem Cells (undifferentiated, Hair shaft, RBCs ) 2. Morphallaxis

Regeneration Types of Regeneration: 1. Stem Cells (undifferentiated, Hair shaft, RBCs ) 2. Morphallaxis (Hydra) 3. Epimorphosis (Amphibian limb, Flatworm) 4. Heteromorphosis (shrimp- Palinurus) 5. Compensatory Regeneration (differentiated, Liver)

- Morphallaxis- lost body parts are replaced by remodeling of remaining part. -Occurs in

- Morphallaxis- lost body parts are replaced by remodeling of remaining part. -Occurs in Planarians- Flatworm -Epimorphosis- requires active cell proliferation before replacement -Occurs in limb and fin regeneration, urodele amphibian-salamander and teleost fish

Pattern Formation Regeneration Epimorphosis

Pattern Formation Regeneration Epimorphosis

Regeneration Epimorphosis Limb regeneration - Blastema What is necessary for limb regeneration? Denerve then

Regeneration Epimorphosis Limb regeneration - Blastema What is necessary for limb regeneration? Denerve then amputated ? Amputation add NGF ? Nerve transplants in animals which normally lack regeneration: Newborn Opposum 1. Hindlimb Amputation ? 2. Supplemental nerve tissue ?

Epimorphosis

Epimorphosis

Epimorphosis characterized by formation of a blastema after wound healing http: //www. eb. tuebingen.

Epimorphosis characterized by formation of a blastema after wound healing http: //www. eb. tuebingen. mpg. de/departments/3 -genetics/zebrafish/christopher-antos/regeneration Zebrafish caudal fin after wound healing Bl=Blastema, We=Wound epidermis

Blastema is a mass of undifferentiated cells capable of growth and regeneration resulting from

Blastema is a mass of undifferentiated cells capable of growth and regeneration resulting from dedifferentiation of cells.

Zebrafish used as model organism for studies regeneration Most studies done on caudal fin

Zebrafish used as model organism for studies regeneration Most studies done on caudal fin -more accessible for surgery and manipulations

Fin regeneration divided into four successive steps 1. Wound healing 2. Blastema formation 3.

Fin regeneration divided into four successive steps 1. Wound healing 2. Blastema formation 3. Regenerative outgrowth concomitant to differentiation 4. Patterning of blastema http: //www. eb. tuebingen. mpg. de/departments/3 -genetics/zebrafish/christopher-antos/regeneration

Hydra freshwater cnidarian Morphallaxis

Hydra freshwater cnidarian Morphallaxis

Hydra – regeneration gradients Head Activator vs. Head Inhibitor both from Hypostome Budding -

Hydra – regeneration gradients Head Activator vs. Head Inhibitor both from Hypostome Budding - level of HA at gastric bud Role of nerves

Compensatory Regeneration (hepatocyte, transforming, epidermal, neural GFs)

Compensatory Regeneration (hepatocyte, transforming, epidermal, neural GFs)

Factors Controlling Regeneration 1. 2. 3. 4. 5. nervous system. animal size. pituitary gland.

Factors Controlling Regeneration 1. 2. 3. 4. 5. nervous system. animal size. pituitary gland. Vitamin A and its derivatives. Insulin.