In this article we will discuss about the structure of endoplasmic reticulum. This will also help you to draw the structure and diagram of endoplasmic reticulum.
1. It was discovered by Porter (1945) as fine recticulum in endoplasm of cells and named as endoplasmic reticulum (E.R.).
2. It is a complex interconnecting system of flattened membrane-surrounded channels and vesicles (cisternae) that spreads throughout the cytoplasm of eukaryotic cells.
3. The membranes appear to be continuous with the plasma membrane at the outer surface and with the nuclear membrane and vacuolar membrane (tonoplast).
4. Some cisternae of ER have a granular appearance in electron micrographs. This is due to ribosomes attached on them. Such an endoplasmic reticulum is called granular or rough endoplasmic reticulum.
5. Other cisternae are devoid of ribosomes and are called agranular or smooth endoplasmic reticulum (Fig. 298).
6. In the channels of rough endoplasmic reticulum are present polypeptides.
7. The main functions of the endoplasmic reticulum include the segregation of newly synthesized products and their further processing and intracellular transport.