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Regeneration is different from reproduction. For example, hydra perform regeneration but reproduce by the method of budding. The regenerative process occurs in two multi-step phases: the preparation phase and the redevelopment phase. [10] [11] Regeneration begins with an amputation which triggers the first phase.
The terminal cell elongates more than the deeper cells; then the production of a lateral bisector takes place in the inner fluid, which tends to divide the cell into two parts, of which the deeper one remains stationary, while the terminal part elongates again, forms a new inner partition, and so on.
The consequence of this asexual method of reproduction is that all the cells are genetically identical, meaning that they have the same genetic material (barring random mutations). Unlike the processes of mitosis and meiosis used by eukaryotic cells, binary fission takes place without the formation of a spindle apparatus on the cell.
Since the reproduction is asexual, the newly created organism is a clone and, excepting mutations, is genetically identical to the parent organism. Organisms such as hydra use regenerative cells for reproduction in the process of budding. In hydra, a bud develops as an outgrowth due to repeated cell division at one specific site.
The cells that contain the determinant become a signaling center and emit an inducing factor. Because the inducing factor is produced in one place, diffuses away, and decays, it forms a concentration gradient, high near the source cells and low further away.
It is the result of increased cell mitosis or division (also referred to as cell proliferation). The two types of physiologic hyperplasia are compensatory and hormonal. Compensatory hyperplasia permits tissue and organ regeneration. It is common in epithelial cells of the epidermis and intestine, liver hepatocytes, bone marrow cells, and ...
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The typical normal human fetal cell will divide between 50 and 70 times before experiencing senescence. As the cell divides, the telomeres on the ends of chromosomes shorten. The Hayflick limit is the limit on cell replication imposed by the shortening of telomeres with each division. This end stage is known as cellular senescence.