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.