1. Is the fault in the components that perform any physical action?
Answer: Yes
2. Is the fault in components that move?
Answer: No
3. Is the fault in the mechanisms controls?
Answer: Yes
4. Is the fault in the components responsible for sending signals?
Answer: Yes
5. Is the fault only limited to non-sensory components?
Answer: No
96) Eastern (red-spotted) newt, Notophthalmus viridescens
Eastern (red-spotted) newts can be found in the eastern states of the United States and the adjacent southern land of Canada (IUCN SSC Amphibian Specialist Group 2014). These newts have the ability of regenerating their spinal cord and central nervous system if it was to get injured.
Soon after the spinal cord has been injured neural stem and radial glial cells start to dedifferentiate and proliferate to form a mesenchymal blastema over the wound (Chernoff). The cells in the blastema start to differentiate into ependymal cells that join with the extracellular matrix to form the cranial and caudal ependymal outrgowths that connect the two cut ends of the spinal cord (Chernoff). Macrophages converge on the wound site to rid it of dead cells or infection. Next the axons are formed from the neural stem cells that proliferated and differentiated. Radial glial cells are then used to create the myelin network that surrounds the axons and protects it from injury. Finally mesenchymal cells proliferate and differentiate into fibrous astrocytes that form the muscles and tissues surrounding the spinal cord (Kageyama & Yamamori). Once the spinal cord, axons, and surrounding muscles are formed the blastema disintegrates and the neural stem and radial glial cells disperse away from the previously injured wound.
IUCN SSC Amphibian Specialist Group 2014. Notophthalmus viridescens. The IUCN Red List of Threatened Species. Version 2014.3. Web. 23 Dec. 2014.
http://www.iucnredlist.org/details/59453/0
Chernoff, Ellen A.G. “Spinal Cord Regeneration: A Phenomenon Unique to Urodeles?” International Journal of Developmental Biology 40 (1996): 823-31. IJDB. Web. 23 Dec. 2014.
www.ijdb.ehu.es/web/descarga/paper/8877457
Kageyama, Ryoichiro, and Tetsuo Yamamori. “Regulatory Mechanisms Underlying the Neurogenesis-to-Gliogenesis Switch by Neural Stem Cells.” Cortical Development Neural Diversity and Neocortical Organization. Dordrecht: Springer, 2013. 63-89. Print.
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