 Hydroplasmic organelle is endoplasmic reticulum. First the contents. Definition of endoplasmic reticulums, location, structure of endoplasmic reticulum and the types of endoplasmic reticulum. First the definition. Endoplasmic reticulum is the complex network of tubules which may be sheet-like, which may be sac-like and they extend from nuclear membrane to the plasma membrane or the cell membrane. They are present throughout the cytoplasm. Students, if we look at the endoplasmic reticulum, all the organelles of cytoplasmic reticulums are extended or extended organelles of endoplasmic reticulum. Endoplasmic reticulum is a rich network of tubules. These tubules are connected to each other. On one side, this network is attached to the nuclear membrane and the outer nuclear membrane. On the other side, this network is attached to the cell membrane. So we can say that the nucleus is directly attached to the cell membrane through the endoplasmic reticulum. With this, the entire cell is extended to the network. Location. Like I just told you, the nucleus is connected to the cell membrane from the nuclear membrane to the cell membrane. The entire cell is connected to an extended network. If we look at it diagrammatically, it is very clear. You can see that all these tubules are connected to the endoplasmic reticulum. If we look at the nucleus at this point, the endoplasmic reticulum is attached to the nuclear membrane. After that, the entire cell membrane is extended and extended to the cell membrane. If you look at the structure of this, you can see that this is an irregular network. This is connected to the cell-like structure of the endoplasmic reticulum. This is a sheet-like structure. We have just discussed that some endoplasmic reticulums are like this, because it is a sheet-like structure. Some of these are like this, because we get the structure of sac-like or irregular type of structure. Now, the different sheet-like structures of the endoplasmic reticulum are basically made up of tubular network. These are called sheet-like tubules or sac-like tubules. Basically, the endoplasmic reticulum is a combination of all these sheets and tubular structures. What we will call the hard tubular structure is called cystrodenium. Overall, all these are cystrodenium, which make up the endoplasmic reticulum. Now, the inside of cystrodenium, which is called limin, the environment of limin is completely different from the environment of cytoplasm. That is why we will have to study that a lot of chemical reactions that cannot be in cytoplasm are in the limin of endoplasmic reticulum. So, the tubular structure of the endoplasmic reticulum and the space in it are called limin. The types of endoplasmic reticulum are two basic types of endoplasmic reticulum. The smooth endoplasmic reticulum and the rough endoplasmic reticulum. The name is indicating rough. Rough means that it gives a rough appearance in the appearance. So, basically, on the endoplasmic reticulum, the rough endoplasmic reticulum is attached to the surface of ribosomes. Due to the attachment of ribosomes, this surface looks rough. So, who are the rough endoplasmic reticulum? Which are having ribosomes on their surface? The surface of ribosomes is on the rough endoplasmic reticulum. Here, in the diagram, you can see that the endoplasmic reticulum on the outside of the nucleus is made of dead red dots. These red dots are attached to the ribosomes on the endoplasmic reticulum. There are some ribosomes and some endoplasmic reticulum on which there is no ribosome attached. On which there is no ribosome attached, that is called the smooth endoplasmic reticulum. Interestingly, rough endoplasmic reticulum and smooth endoplasmic reticulum perform on different functions.