What is endoplasmic reticulum?
a network of membranous tubules within the cytoplasm of a eukaryotic cell, continuous with the nuclear membrane. It usually has ribosomes attached and is involved in protein and lipid synthesis.
The endoplasmic reticulum is a type of cell organelle in the eukaryotic cells. It forms an interconnected network of flattened, membrane-enclosed sacs structures known as cisternae. The membranes of the endoplasmic reticulums are continuous with the outer nuclear membrane and the cell membrane.
The rough endoplasmic reticulums contain ribosomes involved in protein and lipid synthesis, while smooth endoplasmic reticulum lacks ribosomes.