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NRBCs are normally found in the bone marrow of humans of all ages and in the blood of fetuses and newborn infants. [ 2 ] [ 3 ] After infancy, RBCs normally contain a nucleus only during the very early stages of the cell's life, and the nucleus is ejected as a normal part of cellular differentiation before the cell is released into the bloodstream.
As red blood cells contain no nucleus, protein biosynthesis is currently assumed to be absent in these cells. Because of the lack of nuclei and organelles, mature red blood cells do not contain DNA and cannot synthesize any RNA (although it does contain RNAs), [57] [58] and consequently cannot divide and have limited repair capabilities. [59]
In the process of erythropoiesis (red blood cell formation), reticulocytes develop and mature in the bone marrow and then circulate for about a day in the blood stream before developing into mature red blood cells. Like mature red blood cells, in mammals, reticulocytes do not have a cell nucleus.
The normal RBCs count is 4.5 to 5 millions per cu.mm. RBCs have a lifespan of approximately 100-120 days. After they have completed their lifespan, they are removed from the bloodstream by the spleen. Mature red blood cells are unique among cells in the human body in that they lack a nucleus (although erythroblasts do have a nucleus).
The average lifespan of a red blood cell is approximately 120 days. During this maturation process, there is nuclear extrusion – i.e. mature erythrocytes have no nucleus. Nucleated red blood cells present in a sample of bone marrow can indicate the release of incompletely developed cells.
The cell nucleus (from Latin nucleus or nuculeus 'kernel, seed'; pl.: nuclei) is a membrane-bound organelle found in eukaryotic cells.Eukaryotic cells usually have a single nucleus, but a few cell types, such as mammalian red blood cells, have no nuclei, and a few others including osteoclasts have many.
We do need to go back in time a bit, but it's a surprisingly modern tale given how long Christmas has been celebrated. So, let's crack open the history of the Christmas nutcracker!
Cell nucleus: A cell's information center, the cell nucleus is the most conspicuous organelle found in a eukaryotic cell. It houses the cell's chromosomes , and is the place where almost all DNA replication and RNA synthesis ( transcription ) occur.