The Biochemistry of Myelinogenesis in the Central Nervous System
The myelin sheath is built up of many lipoprotein lamellae wrapped around the axon in a continuous sheet of membrane leading from the plasma membrane of the oligodendroglial cell. Immediately before myelination begins, movement of the formative oligodendroglial cells occurs and the glial cell promulgates wrapping, at first, loosely round the axon. At this early stage lipid droplets containing cholesterol esters (1) accumulate in the brain serving, perhaps, as a reservoir of sterol and fatty acids for the needs of the developing tissue. In the rat cholesterol and phospholipid biosynthesis reaches a maximum rate by about 10 days after birth but the most rapid synthesis of sulphatides and cerebroside is further delayed by more than a week. This sequence of change correlates well with the accumulation of lipids in the developing brain (2,3) but not with the histology. Thus in the kitten optic nerve although myelin rings can be easily detected 16 days after birth, the typical myelin constituent is virtually absent, even after 27 days much less galactolipid is detectable than would be anticipated from the morphology (4).
KeywordsMyelin Sheath Oligodendroglial Cell Phospholipid Biosynthesis Myelin Lipid Myelin Fraction
Unable to display preview. Download preview PDF.
- 5.Agrawal, H.C., Banik, N.L., Done, A.H., Davison, A.N. Mitchell, R.F., and Spohn, M. Biochem. J. in press (1970)Google Scholar
- 9.Martenson, R.E., Deibler, G.E., and Kies, M.W., J. biol. Chera. 244:4268 (1969)Google Scholar
- 10.Banik, N.L., and Davison, A.N. Biochem. J. 115:1031 (I969)Google Scholar
- 13.Davison, A.N., p.178 in Applied Neurochemistry (Ed. Davison, A.N., Dobbing J.) 1968Google Scholar
- 14.Davison, A.N., p.547 in Handbook of Neurochem. Vol.3 (Ed. Lajtha, A) 1970Google Scholar
- 15.Smith, M.E., in Adv. in Lipid Res. vol. 5 (Eds. D.Kritchevsky and R. Paoletti) (1967)Google Scholar
- 19.Smith, M.E., Biochim. biophys, Acta 164:285 (1968)Google Scholar
- 23.Rawlins, F.A., Hedley-Whyte, E.T., Villegas, G., Uzman, B.G., in 2nd int.meet. of the int.soc. for Neurochemistry (Eds. R. Paoletti, R. Fumagalli G. Galli) (1969).Google Scholar
- 28.Graham, J.M. and Green, C. Biochem. J. 103:l6C (1967)Google Scholar
- 29.Rouser, G., Nelson, G.J., Fleischer, S., and Simon G., p.5 in Biological Membrane (Ed.hy Chapman, D) London: Academic Press 1968Google Scholar