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Myelin (/ ˈ m aɪ. ə l ɪ n / MY-ə-lin) is a lipid-rich material that surrounds nerve cell axons to insulate them and increase the rate at which electrical impulses (called action potentials) pass along the axon. [1] [2] The myelinated axon can be likened to an electrical wire (the axon) with insulating material (myelin) around it. However ...
The maturation of myelination in intracortical layers coincides with critical period closure in mice, which has led to further research on the role of myelination on critical period duration. [ 37 ] Myelin is known to bind many different axonal growth inhibitors that prevent plasticity seen in critical periods. [ 38 ]
Overview of signal transduction pathways involved in apoptosis. Cell death is the event of a biological cell ceasing to carry out its functions. This may be the result of the natural process of old cells dying and being replaced by new ones, as in programmed cell death, or may result from factors such as diseases, localized injury, or the death of the organism of which the cells are part.
While bubbles made mostly of water tend to burst quickly, oily bubbles are much more stable. The phospholipid, the primary material of cell membranes, is an example of a common oily compound prevalent in the prebiotic seas. [6] Both of these options require the presence of massive amounts of chemicals and organic material in order to form cells.
Individual death – termination of all biological functions within a living organism; Extinction – the death of an entire species, or more specifically, death of the last member of a species Extinction event – a widespread and rapid decrease in the amount of life on Earth. Such an event is identified by a sharp reduction in the diversity ...
The certification applies to somatic death, corresponding to death of the person, which has varying definitions but most commonly describes a lack of vital signs and brain function. [9] Death at the level of cells, called molecular death or cell death , follows a matter of hours later. [ 10 ]
Beginning in the future neck region, the neural folds of this groove close to create the neural tube. The formation of the neural tube from the ectoderm is called neurulation. The ventral part of the neural tube is called the basal plate; the dorsal part is called the alar plate. The hollow interior is called the neural canal. By the end of the ...
A repair process, called remyelination, takes place in the early phases of the disease, but the oligodendrocytes are unable to completely rebuild the cell's myelin sheath. [90] Repeated attacks lead to successively less effective remyelinations, until a scar-like plaque is built up around the damaged axons. [ 90 ]