Axons myelination

The glial cells support the neurons physically. Certain glial cells (oligoden-droglial cells) synthesize myelin, a fatty insulation layer wrapped around the axons. Myelin is necessary for the so-called saltatory conduction of electrical... 

Apoptotic death of oligodendrocytes Slow removal of injured axons, myelin sheaths and persistence of some myelin inhibitory factors No new myelin reforming... 

Our knowledge of the molecular composition of myelin intemodes is substantial, however, we know little about the molecular mechanism responsible for spiral wrapping of myelin membranes or for axon-myelin forming cell communication. 

In addition to the improved structure and cell connectivity, three-dimensional cultures have shown increased survival and enhanced neuronal differentiation compared to traditional mono-layer cultures [36, 37], The increased survival could be related to the improved cell-cell and cell-matrix contact as it leads to improved cell signaling and gap junction connections. Also cellcell signaling can promote proliferation of glial and NSCs that can contribute to increased culture survival. Moreover, the improved cellcell interaction in the 3D structure, especially between astrocytes and neurons, enhances neurogenesis, synapse formation, and axon myelination. 

Neurite growth and axonal myelination is enhanced when fibroblast growth factor is applied in nerve guidance channels (Danielsen et al., 1988), but a positive effect of fibroblast growth factor on axon regeneration in nerves has not been reported. Additional valuable discussion is available (Unsicker et al., 1993). 

Most studies show that iodine deficiency and maternal—fetal hypothyroxinemia have negative effects on fetal neural maturation, dendritic arborization and synaptic formation. It also significantly delays axonal myelinization and gfio-genesis, which starts at the third trimester and accelerates in the postnatal period. Recent studies have clearly demonstrated the necessary role of maternal thyroxine in early neurogenesis (de Escobar et al., 2004 Bernal, 2005). 

Schnaar RL. Brain gangliosides in axon-myelin stability and axon regeneration. FEBS Lett. 2010 584(9) 1741-1747. 

CARS microscopy was used for the study of axonal myelin under physiological conditions in spinal cord, using white matter strips isolated from the spinal cord of guinea pigs and kept alive in oxygen-bubbled Krebs solution. Both forward-and epi-detected CARS were used to probe the axon bundles and resolve detailed structures such as nodes of Ranvier. In addition, simultaneous CARS microscopy of myelin and TEPF imaging of intra- and extra-axonal calcium was demonstrated [58]. 

Chen, Z.-L., Strickland, S., 2003. Laminin gammal is critical for Schwann cell differentiation, axon myelination, and regeneration in the peripheral nerve. J. Cell Biol. 163, 889-899. 

Fruttiger M, Montag D, Schachner M, Martini R. Crucial role for the myelin-associated glycoprotein in the maintenance of axon-myelin integrity. Eur. J. Neuroscl 1995 7 511 515. 

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