Changing glial organization relates to changing fiber order in the developing optic nerve of ferrets
- 7 November 1987
- journal article
- research article
- Published by Wiley in Journal of Comparative Neurology
- Vol. 265 (2), 203-217
- https://doi.org/10.1002/cne.902650205
Abstract
The structures of the developing eye‐stalk and the relationships of early retinofugal fibers as they pass through the stalk, chiasm, and tract have been studied by light and electron microscopical methods in fetal ferrets aged 23–27 days. The early eye‐stalk can be divided into two parts: a narrow extracranial part has a narrow lumen and is lined by few cells, whereas a thicker intracranial part has a wider lumen and is lined by several rows of cells. At the earliest stages no axon bundles are recognizable in the stalk, but fibers of the supraoptic commissure are already beginning to cross the midline in the diencephalon. Subsequently, as retinofugal axons invade the stalk, the glia of the extracranial part of the stalk have an interfascicular distribution and axon bundles are separately encircled by glial cytoplasm. In the intracranial part, as in the chiasm and tract, the glial cells occupy a periventricular position and send slender radial cytoplasmic processes to the subpial surface; these pass between groups of axons that here lie immediately deep to the subpial glia. Whereas axonal growth cones have no evident preferred distribution in the extracranial stalk, they tend to accumulate near the pial surface intracranially. The boundary between the two types of organization shifts as development proceeds so that the interfascicular glial structure of the early extracranial stalk first encroaches upon the intracranial parts and later appears in the chiasm. The characteristic adult arrangement of fibers in an age‐related order in the optic chiasm and tract, but not in the optic nerve, can be understood if axonal growth cones are guided toward the pial surface by radial glia but not by interfascicular glia. From the distribution of the growth cones, this is what appears to happen.Keywords
This publication has 22 references indexed in Scilit:
- Early uncrossed component of the developing optic nerve with a short extracerebral course: A light and electron microscopic study of fetal ferretsJournal of Comparative Neurology, 1987
- Course of retinogeniculate projection fibers in the cat optic nerveJournal of Comparative Neurology, 1986
- Growth cones, dying axons, and developmental fluctuations in the fiber population of the cat's optic nerveJournal of Comparative Neurology, 1986
- The early development of the optic nerve and chiasm in embryonic ratJournal of Comparative Neurology, 1986
- Birth dates of retinal ganglion cells giving rise to the crossed and uncrossed optic projections in the mouseProceedings of the Royal Society of London. B. Biological Sciences, 1985
- Guidance of optic axons in vivo by a preformed adhesive pathway on neuroepithelial endfeetDevelopmental Biology, 1984
- Generation of cat retinal ganglion cells in relation to central pathwaysNature, 1983
- Studies of retinal representations within the cat's optic tractJournal of Comparative Neurology, 1982
- Non-retinotopic arrangement of fibres in cat optic nerveNature, 1979
- The role of cell death during morphogenesis of the mammalian eyeJournal of Morphology, 1973