The lizard can regenerate not only its leg but also the lower jaw, tail, large parts of its brain, heart, and other internal organs such as the pancreas and the kidney. Regeneration is the best method of asexual reproduction in certain protozoans, sponges, coelenterates, and echinoderms. The organism develops from the lost worn-out parts. Members of the kingdom fungi and simple parts such as algae reproduced through unique reproductive structures.
Starfish can regenerate arms, and certain lizards can grow back severed tails. Some flatworms can recreate their entire body from a single adult cell. Also, human skin will grow back together after a paper cut on some level of little regeneration.
How do lizards regrow their tails?
Lizards have the remarkable ability to regenerate their tails through a process called autotomy and subsequent tail regrowth. Here’s an overview of how lizards regrow their tails:
Autotomy: Lizards have a specialized defense mechanism called autotomy, which allows them to detach or shed their tails intentionally. When a lizard is under threat or captured by a predator, it can contract specific muscles to break a predetermined weak point in its tail. The detached tail wriggles and distracts the predator, allowing the lizard to escape.
Wound Healing: The lizard’s body begins healing after the tail is shed. Blood vessels at the base of the tail constrict to minimize bleeding, and a blood clot forms to seal the wound.
Cellular Dedifferentiation: Following the tail loss, specialized cells near the amputation site, called blastemal cells, begin to dedifferentiate. These cells revert to a more primitive, stem cell-like state, capable of producing various cell types needed for tissue regeneration.
Cell Proliferation and Differentiation: The dedifferentiated cells rapidly multiply, forming a cluster or mass of cells called a blastema. The blastema cells proliferate and differentiate into different types of tissues, including muscle, blood vessels, nerves, and skeletal components, such as vertebrae and cartilage.
Pattern Formation: As the tail regenerates, pattern formation occurs. Molecular signals guide the growth and development of the new tail, ensuring proper structure and alignment of tissues. This allows the regenerated tail to resemble the original tail in shape and function.
Tail Regrowth: Over time, the blastema cells continue to differentiate and develop into the tissues necessary to regenerate the tail. Blood vessels extend into the developing tissues to provide nutrients and oxygen, supporting further growth.
Tail Completion: The process of tail regrowth can take several weeks to several months, depending on the species and individual lizard. Eventually, the regenerated tail reaches its entire length and closely resembles the original tail in appearance and functionality, although it may not be an exact replica.
Scientists have figured out how lizards regrow their tails, and that’s good news. By understanding the secret of how lizards regenerate their tails, researchers may be able to develop a way to stimulate the regeneration of limbs in humans. To regrow its tail, the lizard needs to release its tail also. This is done by a process known as autotomy. Lizard’s tail contains three stages for regeneration of their tail.
- Autotomy.
- Wound healing.
- Regeneration.
Autotomy
Autotomy is also called self-amputation. In this process, some lizard detaches their tail from their body. It is a self-defense program done by lizards to protect their predators. When lizard uses their tail, they detach it from the vertebra present in the tail. The vertebra is the 13 individual interlocking bones from the spinal cord.
The tail lives from itself near the vertebra after the detachment. Animals such as womb salamanders and spiders can also do autotomy. Spiders do autotomy when stung in a leg by a vest or bees. Then spider leaves their leg by splitting their venom on their leg to save their life.
Wound healing
To reduce the blood, lizards use a process known as wound healing. Wound healing means the replacement of dead or damaged tissues with new tissue. Every living organism does it. During wound healing in lizards, reticulocyte and epidermal epithelium cells around the worm site cover the wound. The epidermal cell is close to the world. In humans, four steps of wound healing take place.
- First, hemostasis is also known as blood clotting.
- Second inflammation, third low reformation, and fourth maturation.
Hemostasis is when the blood sticks to the injured to make the wound’s healing easier. This blood also acts as a kind of glue. Then inflammation takes place. In this process, damaged and dead cells are cleaned with waste. Proliferation means new tissue is made on the wound. When all this process is done, then final maturation takes place. After the wound-healing process, the unnecessary cells of the body are deleted.
The wound epidermis activates a wave of chemical instructions to the cells below. The nerves in the stump begin to grow again. Mature muscle and tissue cells revert to their immature states before specialized cells. They then start streaming toward the wound, forming a blastema mass. These undifferentiated cells are like stem cells or embryonic cells during development before a gene is activated.
That tells them they will be like a liver, a heart, or a skin cell. But these undifferentiated cells were mature. They have a terrific memory of what they used to be, like a muscle cell in a four-limb or a cartilage cell in a leg joint. They take up their specific positions and form new muscle connective tissue, cartilage, and bone until the animal has a shiny new leg/tail.
Regeneration
Now the part is regeneration. After wound healing, a lot of fibroblasts are blastema. Blastema cell goes to make a new tail. What is a blastema cell? To know that, we need to understand stem cells. In the human body, there are organs like the heart and intestine. These intestines contain intestine cells, and these cells are constantly dying. So there are stem cells that become intestine cells. It happens in all bodies.
Stem cells contain such power that they can become any cell they want like stem cells can become nerve cells and muscle cells. These cells can become only intestine cells if they are present in the intestine. If the stem cell is in the liver, it cannot become bone or muscle cells. They have to become liver cells. Stem cells reproduce with mitosis. Mitosis is a process where a single cell divides into two identical daughters. But stem cells divide into two cells.
The number one cell is called a stem cell, and number two is the cell it wants to become, like a blood cell or any other cell. Stem cells also help in many diseases like Alzheimer’s, heart disease, stroke, burns, cancer, osteoarthritis, etc. After the bone healing process, these stem cells become muscle fibers. So on cells, skeletons make cartilage and bone.
During regeneration, stem cells become only the group of cells known as fibroblasts. Fibroblasts appear to play an essential role in bone healing. The group of fibroblasts now makes another cell known as blastema. This blastema now creates a new tail because blastema contains every cell needed to make a tail, which is how a new tail forms.
- Stem cells make fibroblasts, fibroblasts make blastema, and blastema cells make a new tale.
Lizard’s tail experiment
Once, a scientist named Emler Butler did a very remarkable experiment. Salamander can regrow their whole arm using the entire same process of regeneration. So the scientist tried an exciting experiment in which he cut the rest of the salamander and struck it back into the body.
Also, this made a connection of the limb with the body. Then he cut the elbow, which means now it has two hands. And his two-hand will grow properly using bone healing and regeneration. It was a very remarkable experiment.
Researchers have recently pinpointed a cell that seems to be responsible for salamander’s remarkable regeneration capabilities. All animals have a kind of repair cell called macrophages. They rush into a wound site and eat up dead cells and pathogens while triggering the release of other immune cells.
Mammals also used them to repair muscle which got Dr. James Godwin of the Australian Region of Medicine Institute. Godwin and his colleagues reduced the macrophages at a salamander wound site. They found that regeneration took much longer.
When they removed all the macrophages, the poor guys could no longer regrow limbs but had a lot of scar tissue. So regeneration is possible because those macrophage cells release some vital chemical signal that might trigger the undifferentiated cells to come in and do their thing.
Frequently asked questions
Why can’t humans regrow a new limb?
In humans, regeneration takes a lot of energy. Our body doesn’t want to give a lot of energy. Instead of providing the energy, they habitually use one hand.
Why do lizards lose their tails?
Lizards lose their tail to defend themselves. When they feel attacked or fearful, they remove their tail quickly. It makes a distraction to the predator and gives some time to escape.
Which animals regrow their body parts?
Many animals can regrow their body parts, like Starfish, Deer, Axolotl, Spiders, Sea stars, Skinks, Worms, Conch, Crayfish, Zebrafish, etc.
Does it hurt when lizards lose their tails?
No, losing the tail does not feel hurt. It is a willingness and safety process. Also, it is like a game with a predator!
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References:
Emberts, Z.; Escalante, I.; Bateman, P. W., “The ecology and evolution of autotomy.” Biological Reviews.
Congdon, J.D.; Vitt, L.J.; King, W.W., “Geckos: adaptive significance and energetics of tail autotomy.”
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