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Myelin is formed by oligodendrocytes in the central nervous system and Schwann cells in the peripheral nervous system.Therefore, the first stage of myelinogenesis is often defined as the differentiation of oligodendrocyte progenitor cells (OPCs) or Schwann cell progenitors into their mature counterparts, [4] followed by myelin formation around axons.
There are a variety of symptoms that can occur in children. Infants with microcephaly are born with either a normal or reduced head size. [10] Subsequently, the head fails to grow, while the face continues to develop at a normal rate, producing a child with a small head and a receding forehead, and a loose, often wrinkled scalp. [11]
The process of generating myelin is called myelination or myelinogenesis. In the CNS, oligodendrocyte progenitor cells (OPCs) differentiate into mature oligodendrocytes, which form myelin. In humans, myelination begins early in the 3rd trimester, [ 11 ] although only little myelin is present in either the CNS or the PNS at the time of birth.
The mutation found in an affected individual is not found in either of his or her parents. Symptoms result from the accumulation of Glial fibrillary acidic protein (GFAP) as the result of a mutation in the GFAP gene , whose protein, rather than being found in association with lysosomes or peroxisomes, is an intermediate filament linked to the ...
The pruning that is associated with learning is known as small-scale axon terminal arbor pruning. Axons extend short axon terminal arbors toward neurons within a target area. Certain terminal arbors are pruned by competition. The selection of the pruned terminal arbors follow the "use it or lose it" principle seen in synaptic plasticity. This ...
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 ]
A and B: patient at 1 year (A) and 4 years (B). C: patient, 18 months. D: patient, 13 years. E: patient, 13 years. F: patient, 12 years. Note minor facial dysmorphism: round face, small chin, well-drawn eyebrows in the younger patients; longer face, high and large nasal bridge, long nose, protruding maxilla, in the older patients.
Spontaneous myelin repair was first observed in cat models. [49] It was later discovered to occur in the human CNS as well, specifically in cases of multiple sclerosis (MS). [50] Spontaneous myelin repair does not result in morphologically normal oligodendrocytes and is associated with thinner myelin compared to axonal diameter than normal ...