The regeneration of a limb muscle in the axolotl from minced fragments Supported in part by a Rackham grant and by a grant from the University of Michigan Cancer Institute.

Abstract

In over 50 cases the pubo-ischio-tibialis muscle in mature axolotls was removed, minced and the minced fragments replaced into the site from which the muscle was removed. In 13 control animals the same muscle was removed but nothing was replaced. Regenerates were studied at post-operational intervals of up to 150 days. Both grossly and histologically the regeneration of muscles from minced fragments in the axolotl follows a course very similar to that observed in frogs and rats. There is an initial period of destruction of the sarcoplasm of the minced muscle fragments. This is characterized by intense phagocytic activity. Following this, a population of myoblasts is established and the differentiation of mature muscle fibers ensues. The regeneration of muscles from minced fragments is compared with the formation of muscles in regenerating limbs. Following mincing, new muscle fibers develop rapidly and without the mediation of a blastema. Following limb amputation, a blastema is established before any differentiation of muscle occurs in the regenerate. This occurs more slowly than the differentiation of muscle fibers following mincing. The implications of these differences are discussed.