Endoplasmic Reticulum (ER): Structure and Functions of Rough and Smooth ER

Continuous endoplasmic reticulum network showing rough ER sheets with ribosomes, smooth ER tubules, the ER lumen, and continuity with the outer nuclear membrane.

Endoplasmic reticulum (ER) is a continuous and dynamic membrane system present in the cytoplasm of eukaryotic cells. It is made up of interconnected membranous tubules and flattened sacs called cisternae, enclosing an internal space known as the ER lumen. The membrane network is spread throughout the cytoplasm. Its shape and arrangement can also change within