Path followed:
- Is the fault in the components that perform any physical action?
Answer: Yes
- Is the fault in components that move?
Answer: Yes
- Is the fault in components that make the mechanism move?
Answer: Yes
- Is the faulty component designed to move the mechanism around?
Answer: No
- Is the faulty component a joint?
Answer: No
- Is the faulty component needed for stability?
Answer: Yes
- Does any material need to be removed after regeneration?
Answer: No
33) Mammal, Mammalia
Mammals have become the most complex structures in the world, which is good but one thing they lack is major regenerative abilities. One regeneration capability that mammals do have is the ability to regenerate digits after amputation.
The nail is made of the matrix, cuticle, and lunula. Nail stem cells (NSCs) have been found to reside in the matrix of the nail (Takeo et al.). These cells are used to continually regenerate new nails with the help of the Wntsignal pathway. Once the digit has been amputated the NSCs and Wnt signal pathway direct their attention to regenerating the digit. The Wnt signal pathway attracts nerves that help a blastema form filled with mesenchymal cells (Takeo et al.). Once the blastema is formed the cells undergo dedifferentiation and prolific replication. These new cells will differentiation into muscle, tendons, nerves, and other sensory cells to generate the new digit. Once the digit has been fully regenerated the blastema will degenerate and the mesenchymal cells will go back into the quiescent stage of mitosis.
Takeo, Makoto, Wei Chin Chou, Qi Sun, Wendy Lee, Piul Rabbani, Cynthia Loomis, M. Mark Taketo, and Mayumi Ito. “Wnt Activation in Nail Epithelium Couples Nail Growth to Digit Regeneration.” Nature499.7457 (2013): 228-32. Nature. Web. 2 Dec. 2014.
http://www.nature.com/nature/journal/v499/n7457/full/nature12214.html