Summary
A salamander’s limbs are smaller and slimier than those of people but they are not different from those of human. Its limbs are unique in the world of vertebrates because they can regrow from a stump after an amputation. This ability has been a wonder for the humans since no scar is formed on the skin where the stump as it would in humans. The human body’s healing mechanism is not very different from that of the salamander but the amphibian shows a unique divergent healing strategies. When the salamander limb is amputated, the blood vessels contract immediately limiting bleeding and a layer of skin is cells rapidly covers the area of the amputation site. The area of injury transform into an area of signaling cells called the epithelial cap. The salamander uses a piece of skin together with blastemas to make the amputated limb.
According to lab studies in the University of California, it was demonstrated that the cells in the blastema are equivalent to the cells in the developing appendage bud of the salamander embryo. It was noted that for the regrowth to take place, it required more than the blastemas- fibroblasts from the opposite side of the limb. This proved with the right factors the limb would grow in any part of the salamander. However, variable response indicates that cells must know their location in relation to the entire limb in order to foster regrowth.
Human finger have the ability to regenerate. However the study of human finger regeneration is difficult because it is hard to carry similar studies. Dermis in the human limb lacks the regenerating ability. Like in salamander, wounds in fatal skin like the tongue heal without scars. From the studies conducted science might regenerate human body parts in the future.
Urodele amphibians are unique in that they have the regenerating ability of their body parts. The limb has been extensively studied and the ability noted to progress through a characteristic series of steps, beginning with wound healing, then formation of blastema and finally the redevelopment phase. Studies were carried out using salamanders in the experiments to determine this ability and the limb redevelopment process. First a wound was noticed to heal and the skin regenerated without leaving any scar. Research suggests that if a nerve was deviated to the place of the wound, it would grow to be an entire limb.
Axolotls (Ambystoma mexicanum) were used in an experiment and the results obtained showed that lateral wounds are rapidly covered by epidermis. When a nerve is deviated to a skin wound on either the anterior or posterior side of the limb, a blastema- like outgrowth is induced which eventually grows into a limb. Bumps brought about by a deviated nerve passes a period of rapid growth, unless they also receive a contralateral skin graft they all eventually stop growing and undergo regression. This interferes with the regeneration process.
In absence of regression, bumps that consist of cells from both anterior and posterior skin go on to form limbs. Bumps that progress to form limbs differ histologically from regressing bumps. Bumps and early blastemas are both derived from migrating dermal fibroblasts. They both have the ability to form multifaceted patterns when provided with appropriate positional interactions and fail when they are not. It is therefore right to conclude that bumps are equivalent to early blastemas that happen to be arrested in development and relapse in the absence of positional heterogeneity.
