The endoplasmic reticulum (ER) is a network-like structure of flattened tubes and sacs found inside the cytoplasm of eukaryotic cells.
Image credit - Google.com
The endoplasmic reticulum plays an important role in the synthesis of proteins and lipids.
Image credit - Google.com
Ultrastructure of Endoplasmic reticulum -
Image credit - Google.com
The endoplasmic reticulum forms an elaborate system of flattened tubules or channels in the ground substance of the cells.
Image credit - Google.com
The channels are bounded by membranes that have the same basic structure as the plasma membrane.
Image credit - Google.com
In some cases, these extend from the cell membrane to the outer nuclear membrane and thus establish a continuous system of channels from the external environment to the nucleus.
The endoplasmic reticulum comprises three different components.