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Myelination of prospective large fibres in chicken ventral funiculus
Linköping University, Department of Biomedicine and Surgery, Cell biology. Linköping University, Faculty of Health Sciences.
Linköping University, Department of Biomedicine and Surgery, Cell biology. Linköping University, Faculty of Health Sciences.
Linköping University, Department of Clinical and Experimental Medicine, Cell Biology. Linköping University, Faculty of Health Sciences.
2000 (English)In: Journal of Neurocytology, ISSN 0300-4864, E-ISSN 1573-7381, Vol. 29, no 10, 755-764 p.Article in journal (Refereed) Published
Abstract [en]

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.

Place, publisher, year, edition, pages
2000. Vol. 29, no 10, 755-764 p.
National Category
Medical and Health Sciences
URN: urn:nbn:se:liu:diva-49235DOI: 10.1023/A:1010994505741OAI: diva2:270131
Available from: 2009-10-11 Created: 2009-10-11 Last updated: 2012-09-17Bibliographically approved
In thesis
1. The type IV Oligodendrocyte: experimental studies on chicken white matter
Open this publication in new window or tab >>The type IV Oligodendrocyte: experimental studies on chicken white matter
2002 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

In mammals, islet amyloid polypeptide (IAPP) is co-produced with insulin in pancreatic ß-cells. In the chicken, the expression of IAPP in the brain is more than 10-fold higher than in the pancreas. We made the fortuitous finding that a polyclonal rabbit antiserum raised against chicken IAPP did not recognise the immunogen, but labelled a subpopulation of oligodendroglia! cells in chicken white matter. The hitherto unknown antigen was called T4-O (Type 4 Oligodendrocyte) since it was localised to the Schwann cell-like Type IV oligodendrocyte of Del Rio-Hortega (1928). This formed a starting point for the present thesis, which is centred on the Type IV oligodendrocyte in chicken white matter.

Biochemical analysis of chicken spinal cord showed that the T4-O molecule is a protein with a molecular weight of approximately 100 kDa and an isoelectric point of about 4. Further characterisation has not yet been possible.

Immunohistochemical studies on frozen sections revealed that the white matter oligodendrocytes exhibit subpopulations expressing T4-O immunoreactivity strongly, weakly or not at all. Strongly T4-O immunoreactive (IR) oligodendrocytes are co-localised with thick myelinated fibres in the ventral (VF) and lateral funiculi of the spinal cord. A corresponding T4-O immunoreactivity is not found in the fish, the frog, the turtle, the rat and the rabbit.

To find out when the T4-0 antigen first appears during development we examined sections from embryonic and post-hatching chicken spinal cords by immunohistochemistry. This showed that the T4-O molecule is first expressed in the VF at embryonic day (E)15, after which the number of IR cells increases with age. Oligodendrocytes cultivated in vitro without or with neurons do not develop a T4-O IR phenotype.

These findings called for a closer analysis of the structural development of chicken VF white matter. Electron microscopic (EM) examination revealed a developmental sequence of events principally similar to the development of mammalian white matter, but with a more rapid time course. As seen in the electron microscope the first compact myelin has appeared by E12, when most oligodendrocytes are multipolar. By E15 it seems that these cells have developed a Type IV phenotype, possibly by eliminating some sheaths.

Histochemical analysis of Vibratome sections showed that Marchi-positive myelinoid bodies are enriched in white matter areas containing many T4-O IR oligodendrocytes and many large myelinated axons.

Examination of the three-dimensional (3D) anatomy of early VF oligodendrocytes in Vibratome slices after 04 labelling or after intracellular injection of a fluorescent dye revealed that these units indeed are Schwann cell-like, with a start length of around 50 µm. We also found that these sheaths expand very rapidly, reaching lengths exceeding 200 µm in three days (E12- E15). The 3D data conformed to our EM evidence that the early oligodendrocytes develop a unipolar Schwann cell-like Type IV anatomy through elimination of some sheaths.

To my knowledge the present observations represent the first evidence for an oligodendroglia! heterogeneity in the chicken spinal cord. Differences among oligodendrocytes might, conceivably, explain why inherited disorders of myelin metabolism such as Krabbe's disease, affect some CNS areas more than others.

Place, publisher, year, edition, pages
Linköping: Linköpings universitet, 2002. 96 p.
Linköping University Medical Dissertations, ISSN 0345-0082 ; 720
National Category
Medical and Health Sciences
urn:nbn:se:liu:diva-25545 (URN)9992 (Local ID)91-7373-162-5 (ISBN)9992 (Archive number)9992 (OAI)
Public defence
2002-03-08, Berzeliussalen, Universitetssjukhuset, Linköping, 13:00 (Swedish)
Available from: 2009-10-07 Created: 2009-10-07 Last updated: 2012-12-04Bibliographically approved

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Hildebrand, Claes
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