Phagocytes of the transected feline optic nerve: anultrastructural study
MetadataShow full item record
Following eye enucleation, there is a spatio-temporal pattern of degeneration along the length of the feline optic nerve, and this depends on the proximity of the segment or zone to the transected end. Thus, the rate of axonal degeneration depends on how close it is to the point of excision of the eye. In the proximal and medial segments, degeneration is rapid and the phagocytes originate from extrinsic haematogenous cells, which have invaded the optic nerve from surrounding meningeal blood vessels and capillaries. These phagocytes appear initially around blood vessels and then progressively spread to the parenchyma. In the distal segments, where Wallerian degeneration has occurred, the corresponding process is relatively slow and the phagocytes originate intrinsically. In contrast, these phagocytes are first seen in the parenchyma and then later spread to the blood vessels. Ultrastructurally, these phagocytes share fine features specifically identified with neuroglial cells such as microglia, oligodendrocytes but not astrocytes. For example, these phagocytes are rich in organelles such as mitochondria, ribosomes, microtubules, and rough and smooth endoplasmic reticulum including the Golgi apparatus. Cytoplasmic inclusions such as dense laminar bodies, lipid droplets, lysosomes and lipofuscin granules are also present. Intermediate filaments, seen only in astrocytes, are not found in these phagocytes. Although the study has established that the phagocytes are intrinsic and neuroglial in origin, their true identity is still unresolved. Secondarily, the study has shown that oligodendrocytes continue to survive and remain viable in an axon-free environment. The question about their new role in Wallerian degeneration remains.
This is a pre-copy-editing, author-produced PDF of an article accepted for publication in Journal of Electron Microscopy following peer review.
The definitive publisher-authenticated version:
Chew, Stewart (2007) Phagocytes of the transected feline optic nerve: an ultrastructural study, Journal of Electron Microscopy 56(5):189-202.
is available online at: http://dx.doi.org/10.1093/jmicro/dfm023
Showing items related by title, author, creator and subject.
O'Hare Doig, R.; Bartlett, C.; Maghzal, G.; Lam, M.; Archer, M.; Stocker, R.; Fitzgerald, Melinda (2014)Secondary degeneration contributes substantially to structural and functional deficits following traumatic injury to the CNS. While it has been proposed that oxidative stress is a feature of secondary degeneration, ...
Differential effects of 670 and 830 nm red near infrared irradiation therapy: A comparative study of optic nerve injury, retinal degeneration, traumatic brain and spinal cord injuryGiacci, M.; Wheeler, L.; Lovett, S.; Dishington, E.; Majda, B.; Bartlett, C.; Thornton, E.; Harford-Wright, E.; Leonard, A.; Vink, R.; Harvey, A.; Provis, J.; Dunlop, S.; Hart, N.; Hodgetts, S.; Natoli, R.; Van Den Heuvel, C.; Fitzgerald, Melinda (2014)Red/near-infrared irradiation therapy (R/NIR-IT) delivered by laser or light-emitting diode (LED) has improved functional outcomes in a range of CNS injuries. However, translation of R/NIR-IT to the clinic for treatment ...
Specific ion channels contribute to key elements of pathology during secondary degeneration following neurotraumaO'Hare Doig, R.; Chiha, W.; Giacci, M.; Yates, N.; Bartlett, C.; Smith, N.; Hodgetts, S.; Harvey, A.; Fitzgerald, Melinda (2017)Background: Following partial injury to the central nervous system, cells beyond the initial injury site undergo secondary degeneration, exacerbating loss of neurons, compact myelin and function. Changes in Ca 2+ flux ...