which disease is caused by the breakdown of the myelin sheath that surrounds the axon of the neuron
Myelin Demyelination is the loss of the myelin sheath insulating the nerves, and is the hallmark of some neurodegenerative autoimmune diseases, including multiple sclerosis, acute disseminated encephalomyelitis, neuromyelitis optica, transverse myelitis, chronic inflammatory demyelinating polyneuropathy, Guillain–Barré syndrome, central pontine myelinosis, inherited demyelinating diseases such as leukodystrophy, and Charcot-Marie-Tooth disease. Sufferers of pernicious anaemia can also suffer nerve damage if the condition is not diagnosed quickly. Subacute combined degeneration of spinal cord secondary to pernicious anaemia can lead to slight peripheral nerve damage to severe damage to the central nervous system, affecting speech, balance, and cognitive awareness. When myelin degrades, conduction of signals along the nerve can be impaired or lost, and the nerve eventually withers.[clarification needed] A more serious case of myelin deterioration is called Canavan disease.
Multiple sclerosis While the cause is not clear, the underlying mechanism is thought to be either destruction by the immune system or failure of the myelin-producing cells.[3] Proposed causes for this include genetics and environmental factors such as being triggered by a viral infection.[8][11] MS is usually diagnosed based on the presenting signs and symptoms and the results of supporting medical tests.[4]
Eye injuries during general anaesthesia Methods to prevent intraoperative corneal injuries include
Spermatid When formed, early round spermatids must undergo further maturational events to develop into spermatozoa, a process termed spermiogenesis (also termed spermeteliosis).
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Pericycle Although it is composed of non-vascular parenchyma cells, it is still considered part of the vascular cylinder because it arises from the procambium as do the vascular tissues it surrounds.