Endoplasmic reticulum

Endoplasmic reticulum present in Eukaryotic cells. There are two types of endoplasmic reticulum found in Eukaryotic cells. They are

1. rough endoplasmic reticulum(rER) 
2. smooth endoplasmic reticulum(sER)

They cannot be examined with a light microscope.If we look through an electron microscope we can see the system of membranes running through the cytoplasm of Eukaryotic cell.

 Endoplasmic reticulum shown as a network or reticulum of membranes. We have given a diagram of endoplasmic reticulum and you can obtain some idea about it.

There is a prominent nucleus of the Eukaryotic cells. The nucleus consists of different kind of structures. We will explain about nucleus later.

 We have shown nuclear envelope in the diagram.Because, we can't describe endoplasmic reticulum without mentioning nuclear envelope.Endoplasmic reticulum continues with the nuclear envelope according to the diagram below. It appears as pairs of parallel lines (membranes) running through the cytoplasm . 

In here we have shown two-dimensional of the endoplasmic reticulum. Thus, you can see the surface of the endoplasmic reticulum. The endoplasmic reticulum is composed of multi layers imagined as sheets in three-dimensional perspective. It is usually sheet-like structure rather than tubular.

There is a structure called cisternae found in the endoplasmic reticulum. The cisternae are flattened membrane bound sacs. 

Also, you can see dots like views on the membranes of Endoplasmic Reticulum as shown in diagram. Those are ribosomes. The cisternae covered with ribosomes forming rough endoplasmic reticulum. Sometimes ribosomes are not present in endoplasmic reticulum called smooth endoplasmic reticulum. 

Smooth endoplasmic reticulum have tubular like structure rather than rough endoplasmic reticulum.