endoplasmic reticulum
Last reviewed 01/2018
Endoplasmic reticulum is the network of membrane-lined cavities throughout the cytoplasm of the cell which are continuous with the nuclear envelope and the cell membrane. It separates the outer - cystolic - space from the continuous inner - cisternal - space.
Endoplasmic reticulum is particularly prominent in cells which synthesize large amounts of protein.
There are two key types of endoplasmic reticulum depending on the proportion of ribosomes lining their surface:
- rough endoplasmic reticulum
- smooth endoplasmic reticulum
In practice, the former predominates and there is a spectrum of degrees to which ribosomes are present between the two.