Concentration of astrocytic filaments at the retinal optic nerve junction is coincident with the absence of intra-retinal myelination: comparative and developmental evidence
- 65 Downloads
The structure of the lamina cribrosa (LC) and astrocytic density were examined in various species with and without intra-retinal myelination. Sections of optic nerve from various species were stained with Milligan's trichrome or antibodies to glial fibrillary acidic protein, myelin basic protein (MBP) and antibody O4. Marmoset, flying fox, cat, and sheep, which lack intraretinal myelination, were shown to possess a well-developed LC as well as a marked concentration of astrocytic filaments distal to the LC. Rat and mouse, which lack intraretinal myelination, lacked a well-developed LC but exhibited a marked concentration of astrocytic filaments in this region. Rabbit and chicken, which exhibit intraretinal myelination, lacked both a well-developed LC and a concentration of astrocytes at the retinal optic nerve junction (ROJ). A marked concentration of astrocytes at the ROJ of human fetuses was also apparent at 13 weeks of gestation, prior to myelination of the optic nerve; in contrast, the LC was not fully developed even at birth. This concentration of astrocytes was located distal to O4 and MBP immunoreactivity in human optic nerve, and coincided with the site of initial myelination of ganglion cell axons in marmoset and rat. Myelination proceeded from the chiasm towards the retinal end of the human optic nerve. Moreover, the outer limit of oligodendrocyte precursor cells (OPC) migration into the rabbit retina was restricted by the outer limit of astrocyte spread. These observations indicate that a concentration of astrocytic filaments at the ROJ is coincident with the absence of intraretinal myelination. Differential expression of tenascin-C by astrocytes at the ROJ appears to contribute to the molecular barrier to OPC migration (see Bartsch et al., 1994), while expression of the homedomain protein Vax 1 by glial cells at the optic nerve head appears to inhibit migration of retinal pigment epithelial cells into the optic nerve (see Bertuzzi et al., 1999). These observations combined with our present comparative and developmental data lead us to suggest that the astrocytes at the ROJ serve to regulate cellular traffic into and out of the retina.
Unable to display preview. Download preview PDF.
- ANDERSON, D. R. & HENDRICKSON, A. (1974) Effect of intraocular pressure on rapid axoplasmic transport in monkey optic nerve. Investigative Ophthalmology and Visual Science 13, 771-783.Google Scholar
- BARTSCH, U., FAISSNER, A., TROTTER, J., DÖRRIES, U., BARTSCH, S., MOHAJERI, H. & SCHACHNER, M. (1994) Tenascin demarcates the boundary between the myelinated and non-myelinated part of retinal ganglion cell axons in the developing and adult mouse. Journal of Neuroscience 14, 4756-4768.PubMedGoogle Scholar
- BERLINER, M. L. (1931) Cytological studies on the retina. I. Normal coexistence of oligodendroglia and myelinated nerve fibres. Archives of Ophthalmology 6, 740-751.Google Scholar
- BLUNT, M. J., WENDELL-SMITH, C. P. & BALDWIN, F. (1965). Glia-nerve fibre relationships in mammalian optic nerve. Journal of Anatomy (London) 99, 1-11.Google Scholar
- DUKE-ELDER, S. & COOK, C. (1963) System of Ophthalmology: Normal and Abnormal Development. I. Embryology. p. 119 St. Louis: Mosby.Google Scholar
- GRUMET, M., HOFFMAN, S., CROSSIN, K. L. & EDELMAN, G. M. (1985) Cytotactin, an extracellular matrix protein of neural and non-neural tissues that mediates glia-neuron interaction. Proceedings of the National Academy of Sciences USA 82, 8075-8079.Google Scholar
- MA, N., HUNT, N. H., MADIGAN, M. C. & CHAN-LING, T. (1996) Correlation between enhanced vascular permeability, up-regulation of cellular adhesion molecules and monocyte adhesion to the endothelium in the retina during the development of fatal murine cerebral malaria. American Journal of Pathology 149, 1745-1762.PubMedGoogle Scholar
- MILLIGAN, M. (1946) Trichrome stain for formalin-fixed tissue. American Journal of Clinical Pathology 10, 184-185.Google Scholar
- POTTER, E. L. & GRAIG, J. M. (1975) Pathology of the Fetus and the Infant. Chicago: Yearbook Medical Publishers, pp 29-37.Google Scholar
- SATTLER, C. H. (1915). Ñber die Markscheidenentwicklung im Tractus opticus: Chiasma und Nervus opticus. Albrecht Von Graefes Archiv Fur Ophthalmologie 90, 271-298.Google Scholar
- SKOFF, R., KNAPP, P. E. & BARTLETT, W. P. (1986) Astrocyte diversity in the optic nerve: a cytoarchitectural study. In Astrocytes, Vol. 1. (edited by FEDOROFF, S. & VERNADAKIS, A.) New York: Academic Press. pp 269-291.Google Scholar
- WOLBURG, H. & BÄUERLE, C. (1993) Astrocytes in the lamina cribrosa of the rat optic nerve: Are their morphological peculiarities involved in an altered blood-brain barrier? Journal für Hirnforschung 34, 445-459.Google Scholar