© 1970 by The Society for Integrative and Comparative Biology
Development of Regenerative Ability in the Lizard, Lacerta vivipara
Department of Organismic Biology, School of Biological Sciences University of California at Irvine, California 92664
Department of Anatomy, St. Mary's Hospital Medical School University of London, Paddington, London, IV. 2, England
Among animals which regenerate, it is usually observed that younger forms show greater powers than older ones. It became possible to investigate this correlation in lizards after the development of a culturing technique for the eggs of ovoviviparous reptiles (Panigel, 1956). Moffat and Bellairs (1964) amputated the tails of lizard embryos at various stages and examined them at hatching. Only the embryos amputated at near-hatching stages showed any regeneration. However, subsequent experiments on the younger stages have shown that most of the embryos become constricted and even amputated by the healing amniotic and allantoic membranes. This younger group was therefore re-examined for regenerative ability under conditions where the formation of constrictions could be controlled. The results showed that small asymmetrical outgrowths sometimes arise from a fraction of the stump area. These unusual regenerates were never seen to grow longer than one millimeter, or to differentiate cartilage or muscle. The results suggest that normal regeneration is a process which cannot be elicited until a certain degree of maturity of the tail tissues has been attained, and that it is not necessarily better in young individuals or in tissues which are less well differentiated.