This site says:

In cell biology, microsomes are vesicle-like artifacts re-formed from pieces of the endoplasmic reticulum (ER) when eukaryotic cells are broken-up in the laboratory; microsomes are not present in healthy, living cells.

Whereas this other site says:

Microsome is another name for the smooth endoplasmic reticulum (ER).

Are they both correct? Which one is correct?

  • $\begingroup$ Google says "microsome ˈmʌɪkrəsəʊm/ nounBIOLOGY a fragment of endoplasmic reticulum and attached ribosomes obtained by the centrifugation of homogenized cells." $\endgroup$ – another 'Homo sapien' Dec 29 '16 at 10:17
  • $\begingroup$ Or see this $\endgroup$ – another 'Homo sapien' Dec 29 '16 at 10:18
  • $\begingroup$ @Metroplex so second site must use the word fragment? $\endgroup$ – JM97 Dec 29 '16 at 10:21
  • $\begingroup$ Yes it should. $\endgroup$ – another 'Homo sapien' Dec 29 '16 at 10:31

The first quote is correct. 'Microsome' is more of a lab term. This is because, as said they are found (re-formed) after centrifugation and as such aren't seen in an intact cell. Differential centrifugation is a technique used to separate cellular constituents into fractions. To quote,

The microsomal fraction is the pellet produced when the postmitochondrial supernatant is centrifuged at 50,000g for 60 minutes. Microsomes are small vesicles enclosed by a biological membrane. During centrifugation, the endoplasmic reticulum is fragmented into microsomes

The microsomal fraction may also contain pieces from the plasma membranes apart from those from the ER.

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