Lens regeneration in axolotl: new evidence of developmental plasticity
1 Department of Biology and Center for Tissue Regeneration and Engineering, University of Dayton, 300 College Park, Dayton, OH 45469-2320, USA
2 Current address: Institute of Protein Research, Osaka University, 3-2 Yamadaoka, Suita-Shi, Osaka 565-0871, Japan
3 Current address: Faculty of Life and Environmental Sciences, University of Tsukuba, Tennoudai 1-1-1, Tsukuba, Ibaraki 305-8572 Japan
4 Division of Developmental Biology, Cincinnati Children's Hospital Medical Center, 3333 Burnet Ave., Cincinnati, OH 45229, USA
5 Department of Zoology, Miami University, 700 High Street, Oxford, OH 45056, USA
BMC Biology 2012, 10:103 doi:10.1186/1741-7007-10-103Published: 17 December 2012
Among vertebrates lens regeneration is most pronounced in newts, which have the ability to regenerate the entire lens throughout their lives. Regeneration occurs from the dorsal iris by transdifferentiation of the pigment epithelial cells. Interestingly, the ventral iris never contributes to regeneration. Frogs have limited lens regeneration capacity elicited from the cornea during pre-metamorphic stages. The axolotl is another salamander which, like the newt, regenerates its limbs or its tail with the spinal cord, but up until now all reports have shown that it does not regenerate the lens.
Here we present a detailed analysis during different stages of axolotl development, and we show that despite previous beliefs the axolotl does regenerate the lens, however, only during a limited time after hatching. We have found that starting at stage 44 (forelimb bud stage) lens regeneration is possible for nearly two weeks. Regeneration occurs from the iris but, in contrast to the newt, regeneration can be elicited from either the dorsal or the ventral iris and, occasionally, even from both in the same eye. Similar studies in the zebra fish concluded that lens regeneration is not possible.
Regeneration of the lens is possible in the axolotl, but differs from both frogs and newts. Thus the axolotl iris provides a novel and more plastic strategy for lens regeneration.