Limb Regeneration

Cells keep a memory of their tissue origin axotol limb regeneration. : 

Cells keep a memory of their tissue origin axotol limb regeneration. Dedifferentiated cells is a thing of the past – undifferentiated progenitors ARE the blastema! September 22,2009 Thomas Van Hoose - Terpsichore Lindeman University of Kentucky

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Observation of limb regeneration was observed And questions arose beginning with… Aristotle Thomas Morgan Hunt Dr. Voss- UKY Dr. Gardiner UC Dr Muneoka Tulane Spallanzani

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What is Limb Regeneration? It is defined as the action of  growth anew of lost tissue or destroyed parts or organs There are TWO phases

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There are 3 types of regeneration. Adult cells actually dedifferentiate forming a mass cells That seem to obtain – or actually be respecified! One example of this is the liver Cells divide and maintain their dedifferentiated functions. Regeneration- on a reduced scale of a body part; observed especially in invertebrates such as certain lobsters  and hydra Dedifferentiated Wonder what that looks like …. Simple clip

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Words – Terminology And more terms to learn! GFP Green Fluorescent Protein Gene derived from Jellyfish (Aequorea victoria) Fluorescence under blue light Low toxicity

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This is a multi part experiment! Salamander stained with GFP! Salamander no GFP! Hand with half GFP half no GFP? Place of amputation/graft Place of amputation/graft A closer look….

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NON-GFP GFP GFP MUSCLE GFP PRESENT GFP PRESENT GFP PRESENT NO GFP? NO GFP? GFP PRESENT

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Merging them we have.. NO GPF ABOVE LINE

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So far it is shown that… During

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Schwann cells give rise to Schwann cells EVEN during nerve-rescue of irradiated limbs HAND

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More Nomenclature! Schwann Cells NCAM has been implicated as having a role in cell-cell adhesion,[1] neurite outgrowth, synaptic plasticity, and learning and memory. GFAP has also been located in rat kidney glomeruli and peritubular fibroblasts, leydig cells of testis, skin keratinocytes, osteocytes of bones, chondrocytes of epiglottis, bronchus, and stellate-shaped cells of the pancreas and liver.

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GFP + cartilage not from Schwann derived cells but other nerve cells????

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Positional identity is tissue specific

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In summary…

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-Cells do not become pluripotent during limb regeneration in salamanders -Cells retain a strong memory of their tissue or embryonic origin -The blastema is a heterogeneous pool of restricted progenitor cells -Proximo-distal positional identity is a tissue-specific property of blastema cells