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Evolution provides different myelin sheathing cells (Oligodendrocyte and Schwann cells) in mammalian CNS and PNS. Damaged neurons in the CNS have little chance of recovery whereas damaged neurons in the PNS have an excellent chance of recovery. When ruptured, olidodendrocytes release Nogo that signals the damaged neuron cell body to stop any attempt at regrowing its axonal stump. Ruptured Schwann cells in the PNS do not release Nogo. Why should nature behave like this? Is it because the wiring density of the CNS is orders of magnitude greater than that of the PNS?

Evolution provides different myelin sheathing cells (Oligodendrocyte and Schwann cells) in mammalian CNS and PNS. Damaged neurons in the CNS have little chance of recovery whereas damaged neurons in the PNS have an excellent chance of recovery. When ruptured, olidodendrocytes release Nogo that signals the damaged neuron cell body to stop any attempt at regrowing its axonal stump. Ruptured Schwann cells in the PNS do not release Nogo. Why should nature behave like this? Is it because the wiring density of the CNS is orders of magnitude greater than that of the PNS?

Or could it be because in the PNS the nerve is encased in a perineurial sheath that can readily self-repair and provide a framework for axon regeneration? There doesn't appear to be any similar sheath in the tightly packed CNS. Therefore to prevent unstructured axon regrowth, that could cause chaos in the brain, such a possibility is actively prevented?

Evolution provides different myelin sheathing cells (Oligodendrocyte and Schwann cells) in mammalian CNS and PNS. Damaged neurons in the CNS have little chance of recovery whereas damaged neurons in the PNS have an excellent chance of recovery. When ruptured, olidodendrocytes release Nogo that signals the damaged neuron cell body to stop any attempt at regrowing its stump. Ruptured Schwann cells in the PNS do not release Nogo. Why should nature behave like this? Is it because the wiring density of the CNS is orders of magnitude greater than that of the PNS?

Evolution provides different myelin sheathing cells (Oligodendrocyte and Schwann cells) in mammalian CNS and PNS. Damaged neurons in the CNS have little chance of recovery whereas damaged neurons in the PNS have an excellent chance of recovery. When ruptured, olidodendrocytes release Nogo that signals the damaged neuron cell body to stop any attempt at regrowing its axonal stump. Ruptured Schwann cells in the PNS do not release Nogo. Why should nature behave like this? Is it because the wiring density of the CNS is orders of magnitude greater than that of the PNS?

Evolution provides different myelin sheathing cells (Oligodendrocyte and Schwann cells) in mammalian CNS and PNS to the detriment of CNS neuron damage recovery. Why was this necessary, was it due to the extreme difference in wiring density in the CNS?

Evolution provides different myelin sheathing cells (Oligodendrocyte and Schwann cells) in mammalian CNS and PNS. Damaged neurons in the CNS have little chance of recovery whereas damaged neurons in the PNS have an excellent chance of recovery. When ruptured, olidodendrocytes release Nogo that signals the damaged neuron cell body to stop any attempt at regrowing its stump. Ruptured Schwann cells in the PNS do not release Nogo. Why should nature behave like this? Is it because the wiring density of the CNS is orders of magnitude greater than that of the PNS?