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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.
During regeneration, only cartilage cells can form new cartilage tissue, only muscle cells can form new muscle tissue, and so on. The dedifferentiated cells still retain their original specification. [12] To begin the physical formation of a new limb, regeneration occurs in a distal to proximal sequence. [17]
In humans with non-injured tissues, the tissue naturally regenerates over time; by default, new available cells replace expended cells. For example, the body regenerates a full bone within ten years, while non-injured skin tissue is regenerated within two weeks. [2] With injured tissue, the body usually has a different response.
These cell divisions are usually rapid with no growth so the daughter cells are half the size of the mother cell and the whole embryo stays about the same size. They are called cleavage divisions. Mouse epiblast primordial germ cells (see Figure: "The initial stages of human embryogenesis ") undergo extensive epigenetic reprogramming. [ 16 ]
Endogenous regeneration in the brain is the ability of cells to engage in the repair and regeneration process. While the brain has a limited capacity for regeneration, endogenous neural stem cells , as well as numerous pro-regenerative molecules, can participate in replacing and repairing damaged or diseased neurons and glial cells .
Regeneration: Some organisms can regenerate body parts. The production of new cells in such instances is achieved by mitosis. For example, starfish regenerate lost arms through mitosis. Asexual reproduction: Some organisms produce genetically similar offspring through asexual reproduction. For example, the hydra reproduces asexually by budding ...
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.
The cell cycle, or cell-division cycle, is the sequential series of events that take place in a cell that causes it to divide into two daughter cells. These events include the growth of the cell, duplication of its DNA ( DNA replication ) and some of its organelles , and subsequently the partitioning of its cytoplasm, chromosomes and other ...