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Sökning: WFRF:(Bjartmar Carl)

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1.
  • Anderson, Emma, 1975-, et al. (författare)
  • Oligodendrocytens nyckelroll
  • 2000
  • Ingår i: Läkartidningen. - 0023-7205 .- 1652-7518. ; 97, s. 3265-3268
  • Tidskriftsartikel (populärvet., debatt m.m.)
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2.
  • Anderson, Emma S., 1975-, et al. (författare)
  • Developing chicken oligodendrocytes express the type IV oligodendrocyte marker T4-O in situ, but not in vitro
  • 2000
  • Ingår i: Neuroscience Letters. - 0304-3940 .- 1872-7972. ; 284:1-2, s. 21-24
  • Tidskriftsartikel (refereegranskat)abstract
    • Accumulating data suggest that the oligodendrocyte population includes morphological and biochemical subtypes. We recently reported that a polyclonal antiserum against an unknown antigen, the T4-O molecule, labels a subpopulation of chicken oligodendrocytes, obviously representing the type IV variety of Del Rio Hortega. The present study examines the developmental expression of the T4-O molecule in situ and in vitro. The results show that T4-O immunoreactive cells first appear at E15 in the ventral funiculus. But, oligodendrocytes cultured in vitro with or without neurones do not develop a T4-O immunoreactivity. We conclude that oligodendrocytes in the spinal cord of chicken embryos first express the T4-O molecule some time after onset of myelination, and that the T4-O immunoreactive phenotype does not develop in vitro.
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3.
  • Anderson, Emma S., 1975-, et al. (författare)
  • Molecular heterogeneity of oligodendrocytes in chicken white matter
  • 1999
  • Ingår i: Glia. - 0894-1491 .- 1098-1136. ; 27:1, s. 15-21
  • Tidskriftsartikel (refereegranskat)abstract
    • The classical studies by Del Rio Hortega (Mem. Real. Soc. Espan. Hist. Nat. 14:40–122, 1928) suggest that the oligodendrocyte population includes four morphological subtypes. Recent data from the cat and the rat show that the anatomy of oligodendrocytes related to early myelinating prospective large fibers differs from that of oligodendrocytes related to late myelinating prospective small fibers. After application of a polyclonal antiserum to cryostat sections from the chicken CNS, we noted that glial cells in the spinal cord white matter had become labeled. Analysis of the occurrence and cellular localization of this immunoreactivity—the T4-O immunoreactivity—in the CNS of the adult chicken showed that T4-O immunoreactive cells are enriched in the ventral funiculus and superficially in the lateral funiculus of the spinal cord, where they are co-localized with large fibers. Double staining with T4-O antiserum and anti-GFAP or the lectin BSI-B4 revealed that T4-O immunoreactive cells are not astrocytes or microglia. Staining with anti-HSP108, a general marker for avian oligodendrocytes, showed that T4-O immunoreactivity defines an oligodendroglial subpopulation. A search for T4-O immunoreactivity in spinal cord white matter of some other vertebrates revealed that T4-O immunoreactive cells are not present in sections from fish, frog, turtle, rat, and rabbit spinal cord white matter. These results suggest the presence of a fiber size-related molecular heterogeneity among chicken white matter oligodendrocytes.
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4.
  • Anderson, Emma S., et al. (författare)
  • Myelination of prospective large fibres in chicken ventral funiculus
  • 2000
  • Ingår i: Journal of Neurocytology. - 0300-4864 .- 1573-7381. ; 29:10, s. 755-764
  • Tidskriftsartikel (refereegranskat)abstract
    • In mammals, the oligodendrocyte population includes morphological and molecular varieties. We reported previously that an antiserum against the T4-O molecule labels a subgroup of oligodendrocytes related to large myelinated axons in adult chicken white matter. We also reported that T4-O immunoreactive cells first appear in the developing ventral funiculus (VF) at embryonic day (E)15, subsequently increasing rapidly in number. Relevant fine structural data for comparison are not available in the literature. This prompted the present morphological analysis of developing and mature VF white matter in the chicken. The first axon-oligodendrocyte connections were seen at E10 and formation of compact myelin had started at E12. Between E12 and E15 the first myelinating oligodendrocytes attained a Schwann cell-like morphology. At hatching (E21) 60% of all VF axons were myelinated and in the adult this proportion had increased to 85%. The semilunar or polygonal oligodendrocytes associated with adult myelinated axons contained many organelles indicating a vivid metabolic activity. Domeshaped outbulgings with gap junction-like connections to astrocytic profiles were frequent. Oligodendrocytes surrounded by large myelinated axons and those surrounded by small myelinated axons were cytologically similar. But, thick and thin myelin sheaths had dissimilar periodicities and Marchi-positive myelinoid bodies occurred preferentially in relation to large myelinated axons. We conclude that early oligodendrocytes contact axons and form myelin well before the first expression of T4-O and that emergence of a T4-O immunoreactivity coincides in time with development of a Type IV phenotype. Our data also show that oligodendrocytes associated with thick axons are cytologically similar to cells related to thin axons. In addition, the development of chicken VF white matter was found to be similar to the development of mammalian white matter, except for the rapid time course.
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5.
  • Bjartmar, Carl (författare)
  • On the relation between nerve fibres and glial cells
  • 1996
  • Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
    • The general aim of this study is to generate knowledge on the normal axo-glial relations in developing and adult vertebrate white matter. CNS and PNS specimens from developing and mature rats and from chickens of various ages were analysed through electron microscopy of single and serial sections, or through immunohistochemistry. Sections from fish, frog and turtle were examined by immunohistochemistry. Teased nerves from adult rats were subjected to light microscopic analysis. In addition, Western blot analysis was performed on material from adult chicken spinal cord.At onset of myelination, oligodendrocytes related to prospective large myelinated axons in the ventral funiculus of the spinal cord contact fewer axons than oligodendrocytes related to axons in the cotpus callosum, which are destined to remain small. This difference increases with time. In addition, the data suggest that some spinal oligodendrocytes in the rat reduce the number of sheaths initially elaborated, before formation of compact myelin. In the chicken, the T4-0 antiserum recognizes a single 50 kDa protein. Staining with different markers for glial cells indicate that the T4-0 immunoreactivity is located mainly to a subgtoup of white matter oligodendrocytes in the ventral funiculus, being colocalized with large fibres which myelinate early during development. The T4-0 molecule is expressed after onset of myelination. It can not be detected in fish, amphibian, reptile and mammalian white matter. These results suggest that oligodendrocytes in the rat and in the chicken form a heterogeneous population and that this heterogeneity is related to time of onset of myelination and prospective axon diameter.In the ventral root L5 of newborn rats, the average Schwann cell sheath is 60-70 Jlm long at onset of myelination. The corresponding adult myelin sheath length is 1250 Jlm. While the sheaths exhibit a developmental elongation of 17 times, the root elongates 11 times only. In developing rat white matter, uncompacted oligodendroglia! sheaths are 21-33 Jlm long, many sheaths being <10 Jlm. The average sheath containing cytoplasmic segments and compact myelin is 102 Jlm long in the spinal cord and 69 Jlm long in the cotpus callosum. The intercalated naked axon portions present are too short to accomodate the developmental sheath elongation. These data show that PNS and CNS initial sheath lengths are markedly different, and indicate that both sheath types undergo an early remodelling.Nodes along thin callosal axons possess tiny node gaps with few or no astrocytic processes. Nodes along thick spinal axons have large node gaps containing scattered astrocytic processes. Antibodies against HNK-1, chondroitin sulfate (CS), tenascin or NSP-4labellarge but not small nodes. These data indicate that the relation between nodal complexity and fibre size is less strict in the CNS than in the PNS and that CS occurs at CNS nodes.
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  • Resultat 1-6 av 6

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