Stem Cell Lineage
Stem cells form the basis behind which the human body and the bodies of other living organisms successfully develop and maintain themselves over years. Imbued with the natural potential to replicate and “stem” into any other tissue (a process of genetic differentiation that gives them their name), stem cells must regularly go through two separate processes on a regular basis in order to maintain functionality: symmetric replication and asymmetric replication.
Symmetric replication is a process where a single stem cell divides into two identical daughter cells, each containing the initial stem cell ability to replicate additional stem cells. This allows for stem cells to regularly grow and replace dead or damaged cells without lessening their numbers, closing off systems that would otherwise be compromised without their presence.
Asymmetric replication, on the other hand, creates what is known as a progenitor cell in addition to a standard stem cell. Progenitor cells unlike stem cells can only replicate a certain number of times before being forced to permanently differentiate into a specific cell structure and become part of a set body system. This process both works to limit stem cell population growth as well as allow for the stem cells to assist other structures as necessary – their primary role in maintaining body functionality through ensured system sustainability.
Currently there are two primary theories as to why stem cells go through symmetric division at one point and asymmetric at another. One theory is that the protein receptors found within the cell membrane of each daughter cell determine at any given time whether or not the cell will be a symmetric or asymmetric offspring, adjusting based upon specific codes within the original stem cell that may be received through the body’s natural messaging processes.
A second theory, on the other hand, states that stem cells replicate either symmetrically or asymmetrically based upon environmental factors that surround them at any given time. While in a set environment, for instance, they retain symmetric division, however as new elements are introduced into their environment the cells react accordingly and differentiate to meet their specific needs. Studies have shown this to be an active factor in cell division within some organic structures, however the lack of applicability to all systems (at least the proven lack at this time) means that this is still but a theory and not a proven scientific principal as of yet.
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