Myelinogenesis in optic nerve. A morphological, autoradiographic, and biochemical analysis.

Tennekoon, Gihan; Cohen, Steven R.; Price, Donald L.; McKhann, Guy M.

doi:10.1083/jcb.72.3.604

Cited by 101 publications

(31 citation statements)

References 49 publications

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“…This compares with reports of P11 for the rat corpus callosum (Braun et al, 1988), and P6 for the rat optic nerve (Tennekoon et al, 1977). The myelinated patches only become fully confluent by about 6 weeks of age, and even in the adult around 30% of the axons remain unmyelinated (Suzuki and Raisman, 1992;Wyss et al, 1980).…”

Section: Oligodendrocytessupporting

confidence: 75%

Multifocal pattern of postnatal development of the macroglial framework of the rat fimbria

Suzuki

Raisman²

1994

Glia

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The development of the rat fimbria over the first postnatal month is associated with an approximate doubling of the tract diameter, a large increase in the number of glial cells, and the transformation of the prenatal radial glial skeleton into the adult interfascicular glial rows of solitary astrocytes and contiguous myelinating oligodendrocytes. The ventricular zone is reduced from a heterogeneous germinal layer of three or more cells thick at birth to the mature adult unicellular ependyma of homogeneous pale, mitotically inactive cells by the end of the second postnatal week. Mitoses are present throughout the body of the tract at all times, and persist, at reduced levels, in the adult. At birth the interior of the fimbria has only few scattered glial cell nuclei, largely solitary, or at most in longitudinal pairs. Over the first two postnatal weeks, the numbers and density of the interfascicular glia increase continuously. The scattered cells and cell clusters become progressively transformed into longer unicellular rows, which are aligned along the longitudinal axis of the tract, and which finally coalesce to form the continuous regular astrocyte/oligodendrocyte units that make up the interfascicular glial rows of the adult fimbrial glial skeleton. The increased cell packing density of the developing fimbrial glia is associated with a substantial decrease in nuclear and cytoplasmic size. From the end of the second postnatal week, the characteristic, large pale solitary astrocytes, and the smaller, more numerous, densely stained, closely packed oligodendrocytes are recognisable. Immunostaining for glial fibrillary acidic protein shows that immediately after birth the characteristic embryonic pattern of regular parallel radial glial processes starts to be modified by the progressive accumulation of longitudinal astrocytic processes, so the prenatal radial glial framework is rapidly transformed into the adult type of rectilinear array of radial and longitudinal processes. The development of the oligodendrocytes is shown clearly by immunostaining for myelin basic protein in enlarged, cytoplasm-rich, symmetrically placed cell pairs first seen at around P7. At P8-P10, there is a characteristic pattern of simultaneous multifocal maturation in which a single oligodendrocyte in each cluster develops a full complement of parallel, rather varicose myelinating processes. By P14 myelination is becoming confluent, oligodendrocytes are smaller, darker, with little cytoplasm, and individual myelinating processes cannot be discerned. Even at the end of the first postnatal month there are still many immature glia of indeterminate morphology. Myelination tends at first to be concentrated in the region adjacent to the hippocampus, and only reaches completion by the end of the second month.(ABSTRACT TRUNCATED AT 400 WORDS)

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Section: Oligodendrocytessupporting

confidence: 75%

Multifocal pattern of postnatal development of the macroglial framework of the rat fimbria

Suzuki

Raisman²

1994

Glia

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“…The rat optic nerve has been widely used for correlative morphometric, physiologic, and biochemical studies of the CNS because of its structural and functional homogeneity (27,28). In particular, morphometric analysis of optic nerve was performed to evaluate the myelin formation, as neonatal rat optic nerves are entirely unmyelinated and almost all of the axons undergo myelination during maturation (27).…”

mentioning

confidence: 99%

Effects of Dietary Sphingomyelin on Central Nervous System Myelination in Developing Rats

et al. 2003

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Human milk contains sphingomyelin (SM) as a major component of the phospholipid fraction. Galactosylceramide (cerebroside), a metabolite of sphingolipids, increases along with CNS myelination, and is generally considered a universal marker of myelination in all vertebrates. L-Cycloserine (LCS) is an inhibitor of serine palmitoyltransferase (SPT), a rate-limiting enzyme for sphingolipid biosynthesis that is reported to show increased activity with development of the rat CNS. The present study examined the effects of dietary SM on CNS myelination during development in LCS-treated rats. From 8 d after birth, Wistar rat pups received a daily s.c. injection (100 mg/kg) of LCS. From 17 d after birth, the animals were fed an 810 mg/100g of bovine SM-supplemented diet (SM-LCS group) or a nonsupplemented diet (LCS group). At 28 d after birth, the animals were killed and subjected to biochemical and morphometric analyses. The myelin dry weight, myelin total lipid content, and cerebroside content were significantly lower in the SM-LCS and LCS groups than in a group not treated with LCS (the non-LCS group). However, these levels were significantly higher in the SM-LCS group than in the LCS group. Morphometric analysis of the optic nerve revealed that the axon diameter, nerve fiber diameter, myelin thickness, and g value (used to compare the relative thickness of myelin sheaths around fibers of different diameter) were significantly lower in the LCS group than in the other groups, but were similar in the SM-LCS and non-LCS groups. These findings suggest that dietary SM contributes to CNS myelination in developing rats with experimental inhibition of activity. Abbreviations SM, sphingomyelin LCS, L-cycloserine PC, phosphatidylcholine PE, phosphatidylethanolamine PI, phosphatidylinositol PS, phosphatidylserine SPT, serine palmitoyltransferase TLC, thin-layer chromatography SM is composed of phosphocholine as the polar head group and sphingosine as the backbone of the molecule, and it is therefore classified as one of the sphingolipids. Recent studies have demonstrated that sphingolipids are found in all eukaryotic and some prokaryotic organisms (1). These molecules are involved in the regulation of cell growth (2), cell differentiation, and diverse other functions, including cell-substratum interactions and intracellular signal transduction (3, 4). Human milk has a lower content of phospholipids compared with triglycerides. Bitman et al. (5) reported that human milk has a total phospholipid content of approximately 15 to 20 mg/dL, with SM accounting for approximately 37% of the phospholipid fraction. Although many foods contain a small amount of SM (6), its nutritional and physiologic roles have not been fully examined.CNS myelin has a higher lipid content (65-80%) than that of general cell membranes. SM and sphingolipid metabolites, such as cerebroside and sulfatide, are prominent components of the myelin sheath that surrounds the axons of some neurons. This sheath acts as an insulator for nerve impulses and controls the sal...

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“…It is a well-characterized CNS structure that has been used in numerous studies. 27,28 The visual pathways are vulnerable structures to insults such as deficiency diet, drugs of abuse, and alcohol. [29][30][31][32][33][34][35][36][37] In this study, we examined the effect of iron repletion administrated after weaning on the ON development of rats fed with an iron-deficient diet since birth until the postnatal day (PND 21).…”

Section: Introductionmentioning

confidence: 99%

Effectiveness of iron repletion in the diet for the optic nerve development of anaemic rats

Demaman

Melo

Homem

et al. 2009

Eye

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Purpose To compare the process of myelination in the developing optic nerve (ON) of anaemic rats with the subsequent recovery after being fed an iron-recovery diet. Methods In this study, the morphometrical parameters in the ON were assessed by electron microscopy in Wistar rats that were on an iron-deficient diet for 32 days or for 21 days followed by 10 days on an iron-recovery diet. Qualitative and quantitative analyses were performed using representative electron ultramicrographs. Data were analysed by one-way analysis of variance (ANOVA). When differences were detected, comparisons were made using Tukey's post hoc test (Po0.05 was considered to be significant). Results Qualitative analysis of the ONs in anaemic and recovered animals showed a higher rate of deformed axons and increased lamellar separation in the myelin sheath when compared with the respective control group. The ON of the anaemic group showed a reduced mean density of myelinated fibres when compared with the control group. The fibre area ratio, axon area ratio, and myelin area ratio of large axons/small axons in the ONs of the control group showed the highest values for the myelin areas, axon areas, and total fibre areas. The control group showed a significantly higher myelin sheath thickness when compared with the anaemic and recovered groups. Conclusions Our data indicate that iron is necessary for maintenance of the ON cell structure, and that morphological damage from iron deficiency is not easily reverted by iron repletion.

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Myelinogenesis in optic nerve. A morphological, autoradiographic, and biochemical analysis.

Cited by 101 publications

References 49 publications

Multifocal pattern of postnatal development of the macroglial framework of the rat fimbria

Multifocal pattern of postnatal development of the macroglial framework of the rat fimbria

Effects of Dietary Sphingomyelin on Central Nervous System Myelination in Developing Rats

Effectiveness of iron repletion in the diet for the optic nerve development of anaemic rats

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