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- Anderson, Emma S., 1975-
(författare)
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Morphology of early developing oligodendrocytes in the ventrolateral spinal cord of the chicken
- 2003
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Ingår i: Journal of Neurocytology. - 0300-4864 .- 1573-7381. ; 32:9, s. 1045-1053
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Tidskriftsartikel (refereegranskat)abstract
- The oligodendroglial population includes Type I and II cells related to several thin axons, Type III cells with a few processes in relation to relatively thick axons and Type IV cells related to a single thick axon. This structural diversity of oligodendrocytes is accompanied by a molecular heterogeneity. In the chicken spinal cord, oligodendrocytes have begun to contact axons at embryonic day (E)10 and compact sheaths have appeared by E12. At the latter stage, most sheath-forming oligodendrocytes contact more than one axon. At E15, however, each sheath-forming cell seems to have developed a Schwann cell-like anatomy, being related to a single axon. Based on these findings, the present study examines more thoroughly the anatomy of early developing oligodendrocytes in the chicken spinal cord. Examination of slices immunostained with antibodies against the oligodendroglial marker O4 showed that a few positive cells are present at E6, after which the occurrence increases with age. At E12 most immunostained cells have two or more processes. At E15 however, dye-injected oligodendrocytes have developed a Type IV structure. Between E12 and E15, mean sheath length increases about 4×, from 50 µm to over 200 µm, while the length of the spinal cord increases 36% only. This indicates that early oligodendrocytes in chicken white matter develop a Type IV anatomy between E12 and E15 through an elimination of sheaths.
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| 2. |
- Anderson, Emma S., et al.
(författare)
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Myelination of prospective large fibres in chicken ventral funiculus
- 2000
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Ingår i: Journal of Neurocytology. - 0300-4864 .- 1573-7381. ; 29:10, s. 755-764
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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. |
- Jerregård, Helena, et al.
(författare)
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Fibroblast-like cells from rat plantar skin and neurotrophin-transfected 3T3 fibroblasts influence neurite growth from rat sensory neurons in vitro
- 2001
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Ingår i: Journal of Neurocytology. - 0300-4864 .- 1573-7381. ; 29:9, s. 653-663
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Tidskriftsartikel (refereegranskat)abstract
- Our previous finding that skin-derived and muscle-derived molecules can be used to sort regenerating rat sciatic nerve axons evoked questions concerning neuron-target interactions at the level of single cells, which prompted the present study. The results show that dorsal root ganglion (DRG) neurons co-cultured with fibroblast-like skin-derived cells emit many neurites. These have a proximal linear segment and a distal network of beaded branches in direct relation to skin-derived cells. Electron microscopic examination of such co-cultures showed bundles of neurites at some distance from the target cells and single profiles closely apposed to subjacent cells. RNase protection assay revealed that cultivated skin-derived cells express nerve growth factor (NGF), brain derived neurotrophic factor (BDNF), neurotrophin-3 (NT-3) and neurotrophin-4 (NT-4). In co-cultures of DRG neurons and 3T3 fibroblasts overexpressing either of the neurotrophins produced by skin-derived cells the picture varied. NT-3 transfected 3T3 fibroblasts gave a growth pattern similar to that seen with skin-derived cells. Neurons co-cultured with mock-transfected 3T3 fibroblasts were small and showed weak neurite growth. In co-cultures with a membrane insert between skin-derived cells or 3T3 fibroblasts and DRG neurons few neurons survived and neurite growth was very sparse. We conclude that skin-derived cells stimulate neurite growth from sensory neurons in vitro, that these cells produce NGF, BDNF, NT-3 and NT-4 and that 3T3 fibroblasts producing NT-3 mimic the effect of skin-derived cells on sensory neurons in co-culture. Finally the results suggest that cell surface molecules are important for neuritogenesis.
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| 6. |
- Jerregård, Helena
(författare)
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Sensory neurons influence the expression of cell adhesion factors by cutaneous cells in vitro and in vivo
- 2001
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Ingår i: Journal of Neurocytology. - 0300-4864 .- 1573-7381. ; 30:4, s. 327-336
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Tidskriftsartikel (refereegranskat)abstract
- Dorsal root ganglion (DRG) neurons co-cultured with skin-derived fibroblast-like cells (FLCs) show a strong neurite outgrowth. However, when physical contact between FLCs and neurons is prevented with membrane inserts, the DRG neurons exhibit a low survival and a deficient neurite growth. This indicates that cell adhesion molecules influence neuronal survival and neurite growth in co-cultures. The aim of the present study is to find out if selected adhesion molecules are expressed by cultivated FLCs with and without nervous influences, and/or by normal and denervated whole skin. RT-PCR data show that cultured FLCs and denervated skin express L1, N-CAM, N-cadherin and ninjurin, but not neurofascin or TAG-1. However, cultured FLCs exposed to DRG homogenates and innervated skin express N-cadherin only. Following application of neutralizing L1-, N-cadherin- and ninjurin-antibodies (but not N-CAM-antibodies) in the culture medium the mean number of surviving neurons is decreased. Co-cultures incubated with L1-, N-cadherin- or ninjurin-antibodies all show significantly less neurite outgrowth compared to controls. In conclusion, the findings in this paper indicate (i) that FLCs cultured in vitro and denervated whole skin express the cell adhesion factors L1, N-CAM, N-cadherin and ninjurin, (ii) that FLCs treated with neural molecules and innervated whole skin express N-cadherin only, (iii) that L1, N-cadherin and ninjurin are important for DRG neurons co-cultured with FLCs in vitro in terms of survival and neurite extension and (iv) that there may exist subpopulations of DRG-neurons with different sensitivities for N-cadherin- and ninjurin-antibodies.
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| 8. |
- Kozlova, Elena N, et al.
(författare)
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Human dorsal root ganglion neurons from embryonic donors extend axons into the host rat spinal cord along laminin-rich peripheral surroundings of the dorsal root transitional zone
- 1997
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Ingår i: Journal of Neurocytology. - 0300-4864 .- 1573-7381. ; 26:12, s. 811-822
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Tidskriftsartikel (refereegranskat)abstract
- Following dorsal root crush, the lesioned axons regenerate in the peripheral compartment of the dorsal root, but stop at the boundary between the peripheral and the central nervous system, the dorsal root transitional zone. We have previously shown that fibres from human fetal dorsal root ganglia grafted to adult rat hosts are able to grow into the spinal cord, but were not able to specify the route taken by the ingrowing fibres. In this study we have challenged the dorsal root transitional zone astrocyte boundary with human dorsal root ganglion transplants from 5-8-week-old embryos. By tracing immunolabelled human fibres in serial sections, we found that fibres consistently grow around the dorsal root transitional zone astrocytes in laminin-rich peripheral surroundings, and extend into the host rat spinal cord along blood vessels, either into deep or superficial laminae of the dorsal horn, or into the dorsal funiculus. Human fibres that did not have access to blood vessels grew on the spinal cord surface. These findings indicate, that in spite of a substantial growth capacity by axons from human embryonic dorsal root ganglion cells as well as their tolerance to non-permissive factors in the mature mammalian CNS, these axons are still sensitive to the repellent effects of astrocytes of the mature dorsal root transitional zone. Furthermore, this axonal ingrowth is consistently associated with laminin-expressing structures until the axons reach the host spinal cord.
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| 9. |
- Kristensson, K, et al.
(författare)
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Distribution of protein tracers in the nervous system of the crayfish (Astacus astacus L) following systemic and local application
- 1972
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Ingår i: Journal of Neurocytology. - 0300-4864. ; 1, s. 35-48
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Tidskriftsartikel (refereegranskat)abstract
- A study was made on the penetration and cellular uptake of two protein tracers, albumin labelled with Evans blue (EBA) and horseradish peroxidase (HP), in the nervous system of the crayfish following systemic and local administration. Followingsystemic injection, EBA did not diffuse freely from the cerebral vessels into the brain parenchyma. When the tracers werelocally applied on the surface of the ventral nerve cord their penetration into the nervous parenchyma was to some extent restricted by the nerve sheath. However, unlike the perineurium of vertebrate peripheral nerves, which acts as an efficient diffusion barrier, the crayfish nerve sheath allowed the diffusion of small amounts of tracers into the ganglia. The tracers could more readily penetrate into peripheral nerves in the vicinity of ganglia. Inside the ganglion the tracers spread in extracellular spaces, between glial cell membranes and reached the neuronal surfaces. The proteins were taken up by pinocytosis in glial cells, and also in axons.
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