Could Bourriquet’s Tail Be Rejected?

Do you know Bourriquet? He is the little gray plush donkey, friend of Winnie l'Ourson and Jean-Christophe. And, you may have noticed, he is often very sad … in question? He loses his tail a lot, which saddens him. But why wouldn't he do like the lizard? It would be enough to have it “repel” it and everything would be much better! Certainly, but all the animals, including humans, have not developed these superpowers. The fault of evolution …

On the other hand, in reptiles, amphibians, certain crustaceans and other invertebrates, regeneration works very well! These animals thus have the capacity to have a limited member or organ “repel” or amputated.

And where does this supper-power come from? Of particular cells, called stem cells. These cells have proliferation, self -renewal and differentiation capacities. There are several types of stem cells, whose location and becoming differ.
The stem cells are generated by the bone marrow and can circulate in the body. Others are generated directly by the tissues that need it, like those of skin bulbs allowing the regrowth of hair and hair.

In any case, regardless of their origin, stem cells can act to repair and therefore have “pushed” wired tissues and, all the more so, organs.
There are several types of stem cells. Some have the ability to differentiate themselves into any type of cells in the body of the organism. They are called “pluripotent” cells. Among mammals and vertebrates, they are only found at the very beginning of embryonic development. Then, as the embryo is growing and forming, cells specialize and end up losing their pluripotence capacity. They can only give only certain types of fabrics, they are said to be “multipotent”.

These different cellular regeneration capacities explain why some animals can regenerate entirely, while others can only repel certain parts of their body.

>> Read also: the superpowers of the stem cells of human urine!

Animals sources of inspiration for wading … and us!

The idea is not to make a list in the prevert of all animals capable of regenerating all or part of their body, but let's talk about some of these superheroes! Bourrique has only to draw inspiration …

Let's start first with the invertebrates and in particular certain lines. So, yes, the latter will not have arms and legs “repel” … But what do you say about the head? Planar worms, non -parasitic aquatic verses are able to repel everything! And we say everything! A whole worm can reform from any fragment of their body.
Incredible right? And that because all the tissues always have pluripotent stem cells, even in adult state! On the other hand, do not start to cut in half all the low backgrounds you come across, because the idea that a glass of earth cut in two “regrowth” is false! The poor little animal will just be cruelly injured, even die …
Starfish and certain cnidaries, such as Hydra, on the other hand, are also able to regenerate their whole body.

Now let's go to vertebrates and make a detour to fish. We're going to talk about the little zebra fish. He is no longer able to regenerate his whole body, but he can still have a number of tissues and organs “repel”. Rooms, spinal cord, retina, heart, kidneys and even parts of the brain! This fish, star of laboratories, therefore demonstrates great versatility.

We can't talk about regeneration without talking about the axolotl! In reality, the animal is so strange that it deserves an article on its own … This Mexican amphibian, eternal juvenile, can regenerate multiple parts of his body, throughout his life.
However, here, no stem cells, but another mechanism, which is called cellular “dedifferentiation”. When a fabric is injured, the body will “dedicate” the nearby cells, they will thus return to the state of embryonic stem cells, which is called blastem, and will therefore be able to differentiate themselves to reform the damaged tissue, even the member or the organ.

And wing and mammals in all of this?

Axolotl is a Mexican amphibian with multiple powers of regeneration.
Credits: Shutterstock/Lapis2380

>> Read also: This is how the Hydra regenerates his head

Bourriquet is not ready to have his tail “repel” …

Certainly, some vertebrates are able to regenerate their bodies. We have not talked about the lizard, but it is of public notoriety that he is able to have his tail repelled. On the other hand, among mammals, we are still waiting for the feat of regeneration …

So why is Bourriquet not likely to see his tail pushing? The culprit would be evolution, but we are still looking for other suspects.
In “complex” animals (in terms of cell organization), it would become more and more complicated to regenerate organs, members, even an entire organism. This requires the harmonization of an incalculable number of genes and signals … There are too many risks of errors and therefore of the development of tumors and other cancers. Natural selection would therefore have increasingly reduced this regeneration super-power for animals like Bourriquet and us.

Despite everything, mammals are not completely devoid of regeneration capacities. Take the deer for example, they are still able to push 30 kilos of wood in just a few months! It's a great feat! Bat could also regenerate parts of their wings and certain species of mouse, their skin.

We ourselves, humans, can regenerate certain parts of our organs. For example, our skin cells are renewed regularly and we are able to heal wounds, which, certainly leave a scar, but still allow the creation of new cells.
The bone fabrics regenerate every 10 years and the liver is even more impressive, since it can “repel” its lobes, hence the possibility of donating certain parts of this organ.

So, a wing, rest assured, you have a skin that renews itself, hair that grows up … But indeed, you will always duties count on Jean-Christophe to put your tail back!

>> Read also: Neuroscience: neurons can be regenerated!