Newt Limb Regeneration An The Effect Of Double Limb Amputation

Abstract

The ability to regenerate is a fundamental property of living matter. In higher vertebrates, however the regenerative capacity is limited. Most are unable to regenerate appendages. This ability seems to have reached the amphibians, however, before being lost. Urodele amphibians are the most noted for limb regeneration, although anuran larvae also possess this capacity. The adult frog has lost the power to regenerate a limb normally, but through artificial induction, even these can be led to regenerate a limb-like structure (Singer, 1958). Xenopus laevis, a primitive frog (Rostand, 1932), also is capable of regenerating an amputated limb, although the new growth tends to be heteromorphic and occurs less readily after proximal amputation (Beetschen, 1952). This paper is concerned with the phenomenon of limb regeneration in the urodele. The histological processes will be examined and reference will be made to phases of regeneration as outlined by Schotte and Butler (1942) and Singer (1952). Early in the days following limb amputation, cells accumulate to form a regenerate blastema at the tip of the limb stump (Singer, 1952). Research on the origin of these blastema cells points to a dedifferentiation of mesodermal tissues (Chalkley, 1954; Trampusch and Harrebomee, 1965). The importance of the formation of an apical cap from migrating epidermis has also been examined (Thornton, 1957).The ability to regenerate is a fundamental property of living matter. In higher vertebrates, however the regenerative capacity is limited. Most are unable to regenerate appendages. This ability seems to have reached the amphibians, however, before being lost. Urodele amphibians are the most noted for limb regeneration, although anuran larvae also possess this capacity. The adult frog has lost the power to regenerate a limb normally, but through artificial induction, even these can be led to regenerate a limb-like structure (Singer, 1958). Xenopus laevis, a primitive frog (Rostand, 1932), also is capable of regenerating an amputated limb, although the new growth tends to be heteromorphic and occurs less readily after proximal amputation (Beetschen, 1952). This paper is concerned with the phenomenon of limb regeneration in the urodele. The histological processes will be examined and reference will be made to phases of regeneration as outlined by Schotte and Butler (1942) and Singer (1952). Early in the days following limb amputation, cells accumulate to form a regenerate blastema at the tip of the limb stump (Singer, 1952). Research on the origin of these blastema cells points to a dedifferentiation of mesodermal tissues (Chalkley, 1954; Trampusch and Harrebomee, 1965). The importance of the formation of an apical cap from migrating epidermis has also been examined (Thornton, 1957).