Limb Regeneration in Anuran Amphibians
We are already aware that the limb of adult frogs does not regenerate later than amputation. Though, some regeneration has been found to take place in experimental animals. Recovery of regeneration capability in most metamorphic frogs is made possible by tissue trauma and prevention of wound healing. This is acquired by extensive piercing of the amphibian amputaton site with a needle also traumatization by using hypertonic solutions. Normally wound healing in adult anurans is brought about through the movement of the epidermis and the dermis over the wound surface. In contrast just only the epidermis covers the wound in the urodeles.
Generally when a part of the adult anuran is amputated the wound heals by the production of connective tissue from dermal elements (dermalization) and the scarring of injured tissues. Continued injury in some type of way interferes with dermalization and permits a variable amount of regeneration to occur. Similar results of regeneration have been attained by implanting batteries and applying a continuous direct current by fine wire to the amputation area. Superficially this emerges to stimulate action of the nerves. Regeneration also sometimes results from irritation. Implanting of adrenal glands as well appears to prevent dermalization. It has been observed that if larval skin is applied over adult frogs then regeneration becomes possible. Other studies have implicated the wound epithelium as a significant factor in initiating regeneration.