RECOVERY

Regeneration

Picture
Limb regeneration is when a person or animal is actually able to re-grow a limb that may have been lost in an accident or through amputation. Scientific evidence indicates that humans have the potential for limb regeneration in our genes, but those genes are dormant in our bodies, meaning that it would require the activation of those genes if we want our bodies to be able to re-grow limbs. Many animals, specifically salamanders, have the ability to re-grow limbs (and their tails) without having to activate any dormant genes. When a whole limb is lost, the body reacts by covering that wound site with thick scar tissue to protect against infection. This marks the beginning of the initial phase. The initial phase of regeneration involves shuffling around the cells at the wound site and assigning them a new specialization (during the differentiation process, each cell is assigned their first function). More specifically, the salamander's epidermal (skin) cells go to cover the open flesh at the eventual regeneration spot. This layer of cells thickens to form the apical epithelial cap, which covers the stub where the limb was once located. Cells that are located within the salamander's tissues, known as fibroblasts, are also forming beneath the skin. Fibroblasts are special in that they are undifferentiated, which means that they're able to become many different types of cells, depending on the limb/body part that needs replacement. This marks the end of the initial phase, and the beginning of the blastema growth phase. In this phase, the fibroblasts develop into the blastema, which is what will eventually turn into the new limb/tail. However, this process would be too long to be practical without nAG, which is a protein that speeds up the recovery process. The blastema has special properties in that it is able to grow into any limb necessary, because of its current undifferentiated state. In other words, it is able to attach to where the limb once was and differentiate itself into what will be the new limb/tail. The special properties involve the genetic coding in the blastema. The code contains a positional memory about location and type of missing limb/tail. That data is then stored within the fibroblast cells. Simultaneously, blood vessels and other forms of transportation within the limb/tail are reforming into the blastema. While the blastema cells are dividing and multiplying, the mass becomes a group of cells which are undifferentiated. In order for that group to become a whole limb/tail, it has to receive stimulation from different types of nerves. However, the nerves must be regenerated as well, since they are usually lost along with the epidermic layer. Thus completes the process of regeneration!

Blastema

Picture

Sources: