University of Oulu

Alibardi, L.; Meyer-Rochow, V.B. Regeneration in Reptiles Generally and the New Zealand Tuatara in Particular as a Model to Analyse Organ Regrowth in Amniotes: A Review. J. Dev. Biol. 2021, 9, 36.

Regeneration in reptiles generally and the New Zealand tuatara in particular as a model to analyse organ regrowth in amniotes : a review

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Author: Alibardi, Lorenzo1; Meyer-Rochow, Victor Benno2,3
Organizations: 1Comparative Histolab Padova and Department of Biology, University of Bologna, 40121 Bologna, Italy
2Agricultural Science and Technology Research Institute, Andong National University, Andong 36729, Korea
3Department of Ecology and Genetics, Oulu University, SF-90140 Oulu, Finland
Format: article
Version: published version
Access: open
Online Access: PDF Full Text (PDF, 10.8 MB)
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Language: English
Published: Multidisciplinary Digital Publishing Institute, 2021
Publish Date: 2021-11-04


The ability to repair injuries among reptiles, i.e., ectothermic amniotes, is similar to that of mammals with some noteworthy exceptions. While large wounds in turtles and crocodilians are repaired through scarring, the reparative capacity involving the tail derives from a combined process of wound healing and somatic growth, the latter being continuous in reptiles. When the tail is injured in juvenile crocodilians, turtles and tortoises as well as the tuatara (Rhynchocephalia: Sphenodon punctatus, Gray 1842), the wound is repaired in these reptiles and some muscle and connective tissue and large amounts of cartilage are regenerated during normal growth. This process, here indicated as “regengrow”, can take years to produce tails with similar lengths of the originals and results in only apparently regenerated replacements. These new tails contain a cartilaginous axis and very small (turtle and crocodilians) to substantial (e.g., in tuatara) muscle mass, while most of the tail is formed by an irregular dense connective tissue containing numerous fat cells and sparse nerves. Tail regengrow in the tuatara is a long process that initially resembles that of lizards (the latter being part of the sister group Squamata within the Lepidosauria) with the formation of an axial ependymal tube isolated within a cartilaginous cylinder and surrounded by an irregular fat-rich connective tissue, some muscle bundles, and neogenic scales. Cell proliferation is active in the apical regenerative blastema, but much reduced cell proliferation continues in older regenerated tails, where it occurs mostly in the axial cartilage and scale epidermis of the new tail, but less commonly in the regenerated spinal cord, muscles, and connective tissues. The higher tissue regeneration of Sphenodon and other lepidosaurians provides useful information for attempts to improve organ regeneration in endothermic amniotes.

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Series: Journal of developmental biology
ISSN: 2221-3759
ISSN-E: 2221-3759
ISSN-L: 2221-3759
Volume: 9
Issue: 3
Article number: 36
DOI: 10.3390/jdb9030036
Type of Publication: A2 Review article in a scientific journal
Field of Science: 1181 Ecology, evolutionary biology
Funding: The technical-lab part of the study was primarily self-supported (LA, Comparative Histolab). A scholarship provided by the New Zealand Grants Committee allowed LA to visit New Zealand and spend a year in VBM-R’s lab at the University of Waikato in 1987–1988, and in 1991–1992. The New Zealand Department of Conservation and Victoria University of Wellington (Drs. Alison Cree and Michael Thompson) supported the expedition to Stephens Island to observe S. punctatus in the wild during January 1988.
Copyright information: © 2021 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (