Why can't neurons divide? Oct 15, Neurons can not divide after the birth. Explanation: For a cell to divide it should undergo either Mitosis or Meiosis. As neurons are somatic cells then they should undergo Mitosis. For Mitosis to occur, Centrioles should move to the poles and should develop spindle fibers that pull the chromosomes.
Neurons lack the Centrioles and hence Mitosis is not possible and so they can't divide. The answer is simple: because it is super sensitive and very vulnerable. Probably, your skin. Think about a time when you fell, your skin broke open and you had a wound like a scrape or a cut for some time. Or maybe you can see a scar, but basically your skin was able to repair itself almost perfectly. Unfortunately, the brain and spinal cord are fundamentally different.
If your brain gets injured, some damage may persist throughout the rest of your life. After an injury, the skin makes a bunch of new cells and uses them to heal your wound. Yet, nerve cells in your brain, also called neurons , do not renew themselves. They do not divide at all. There are very few exceptions to this rule — only two special places in the brain can give birth to new neurons.
For the most part though, the brain cannot replenish dead neurons. This is especially worrisome because neurons are very sensitive cells and they die for all sorts of reasons. When you bump your head and suffer a concussion , neurons die. When there is a glitch in the blood supply to the brain, also called a stroke , neurons die. Here is the good news. Because loss of neurons is usually permanent, scientists are working on two important strategies to help the brain after injury.
One way is to protect the nervous system immediately after the damage occurs. This damage could be a stroke, a severe concussion, or any kind of injury. If we can somehow limit the number of neurons that die early after injury, then we are keeping the damage to a minimum. To help with repair later on after the injury, after the damage is done, some scientists are trying to use stem cells as a treatment for neuronal loss in the brain.
They have the capacity to develop into brand new neurons if scientists treat them with special molecules. This is a little like elementary school students who are not doctors or plumbers yet, but they have the capacity to become any professional in the future, given the right training. The biggest challenge with replacing dead neurons with stem cells is to have these newcomer neurons integrate, or fit into, the existing brain networks the right way.
Looking at the structure of a neuron, you will notice it has a cell body and several arms that it uses to connect and talk with other neurons Figure 1 , left. The really long arm that sends signals to other neurons is called axon , and axons can be really long. If an axon is damaged along its way to another cell, the damaged part of the axon will die Figure 1 , right , while the neuron itself may survive with a stump for an arm.
The problem is neurons in the central nervous system have a hard time regrowing axons from stumps. Why do skin cells not have this problem? Skin cells are much simpler in structure. First, they need motivation. There are special molecules that help activate growth in neurons. It does seem weird that we can't replace nerve cells that get damaged.
The answer is basically that having nerve cells reproduce can do more harm than good. Each nerve cell has a specific place in our nervous system. Its job is all about taking a signal from one specific place to another one. Adding new nerve cells would mess up these very specific connections in a very complex system. So we trade off the ability to repair our nerves in order to avoid messing up connections.
We used to think that people never got new nerve cells, but it turns out that we get a small number of them around the teen years. This does seem to make life a bit more complicated for young people whose brains have to adjust to the new nerve cells. This is also a good example of how science is constantly discovering new information.
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