Panagiotis A Tsonis, University of Dayton, Dayton, Ohio, USA
Published online: April 2001
DOI: 10.1038/npg.els.0001102
Some vertebrates, especially amphibians, can regenerate the lens after lentectomy. Other structures, such as retina, can also be regenerated. The regeneration process is initiated by the pigment epithelial cells which can transdifferentiate to lens or retina. While a gene responsible for such events is not known, evidence has mounted implicating Hox genes and fibroblast growth factors as key regulators.
Keywords: vertebrates; regeneration; eye; transdifferentiation
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Figure 1.
A section through an adult newt eye to illustrate the basic structures and tissues. nr, neural retina; le, lens epithelium; lf, lens fibres; pe, pigment epithelium; di, dorsal iris; vi, ventral iris; c, cornea. The neural retina and the lens epithelium are stained with a purple/blue colour from the detection of FGF‐1 mRNA. |
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Figure 2.
Histological features in sections during lens regeneration. (a) Dorsal iris 10 days after lentectomy. The tip of the dorsal iris (arrow) has depigmented and dedifferentiated. This is the beginning of the formation of the lens vesicle. (b) Dorsal iris 15 days after lentectomy. The internal layer of the lens vesicle thickens and differentiation of lens fibres starts. (c) Regenerating lens 20 days after lentectomy. Lens differentiation is almost complete. The lens epithelium is covering the lens at the anterior, while lens fibre differentiation is prominent from the posterior lens. The regenerating lens in (a) to (c) is stained with a purple/blue colour from the detection of FGF‐1 mRNA, which is expressed in both the lens epithelium and the lens fibres. (d) Regenerated lens 25 days after lentectomy. This section has been stained for the presence of γ‐crystallin, which is specific for lens fibres. The lens epithelium is not stained. le, lens epithelium; lf, lens fibres; c, cornea; an, anterior; p, posterior. |
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Figure 3.
Transdifferentiation of lentoid bodies in culture of chicken pigment epithelial cells. Note presence of lentoids differentiated from the dissociated cells. lb, lentoid bodies. |
References
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Further Reading
Altman CR, Chow RL, Lang RA and Hemmati‐Brivanlou A (1997) Lens induction by pax‐6 in Xenopus laevis. Developmental Biology 185: 119–123.
Chow RL, Roux GD, Roghani M et al. (1995) FGF suppresses apoptosis and induces differentiation of fibre cells in the mouse lens. Development 121: 4383–4393.
Collins JM (1974) Structural changes in DNA during early stages of lens regeneration in Triturus. Journal of Biological Chemistry 249: 1839–1847.
Eguchi G (1988) Cellular and molecular background of Wolffian lens regeneration. In: Eguchi G et al. (eds) Regulatory Mechanisms in Developmental Processes, pp. 147–158. Amsterdam: Elsevier.
Eguchi G (1993) Lens transdifferentiation in the vertebrate retinal pigmented epithelial cell. In: Progress in Retinal Research, vol. 12, pp. 205–230. Oxford: Pergamon Press.
Halder G, Callaerts P and Gehring WJ (1995) Induction of ectopic eyes by targeted expression of the eyeless gene in Drosophila. Science 267: 1788–1792.
McDevitt DS and Brahma SK (1981) Ontogeny and localization of the α, β, and γ crystallins in newt eye lens development. Developmental Biology 84: 449–454.
Mitashov VI (1996) Mechanisms of retina regeneration in urodeles. International Journal of Developmental Biology 40: 833–844.
Oliver G, Loosli F, Koster R, Wittbrodt J and Gruss P (1996) Ectopic lens induction in fish in response to the murine homeobox gene six‐3. Mechanisms of Development 60: 233–239.
Robinson ML, Overbeek PA, Verran DJ et al. (1995) Extracellular FGF‐1 acts as a lens differentiation factor in transgenic mice. Development 121: 505–514.
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