![This is blank.](https://digitalhistology.org/wp-content/themes/histology-unified/imgs/trans.png)
Membranes
With electron microscopy, membranes appear as dark lines, due to the reaction of osmium with the membrane lipids. At much higher magnification than shown here, membranes show a trilaminar appearance. Membranes are a component of many intracellular organelles, as well as forming the unique membrane at the cell surface, called the plasma membrane. 15,000x
![Plasma membrane > <p>The plasma membrane is the membrane at the cell surface, enclosing the cytoplasm of the cell.</p>](https://digitalhistology.org/wp-content/uploads/2017/05/C.S.M-5-1-ping.png)
Plasma membrane >
The plasma membrane is the membrane at the cell surface, enclosing the cytoplasm of the cell.
![Nuclei > <p>A portion of the nucleus of each cell is visible.</p>](https://digitalhistology.org/wp-content/uploads/2022/05/C.S.M-5-nuclei-ping.png)
Nuclei >
A portion of the nucleus of each cell is visible.
![Nuclear envelope > <p>Two membranes surround each nucleus, forming the nuclear envelope. Arrows indicate the outer nuclear membrane. Intracellular membranes have a similar structure and appearance as the plasma membrane.</p>](https://digitalhistology.org/wp-content/uploads/2022/05/C.S.M-5-membrane-ping.png)
Nuclear envelope >
Two membranes surround each nucleus, forming the nuclear envelope. Arrows indicate the outer nuclear membrane. Intracellular membranes have a similar structure and appearance as the plasma membrane.
![RER > <p>Intracellular membranes, e.g. those forming the endoplasmic reticulum, are also composed of membranes with a similar structure and appearance as the plasma membrane. Rough endoplasmic reticulum is studded with ribosomes.</p>](https://digitalhistology.org/wp-content/uploads/2017/05/C.S.M-5-3-ping.png)
RER >
Intracellular membranes, e.g. those forming the endoplasmic reticulum, are also composed of membranes with a similar structure and appearance as the plasma membrane. Rough endoplasmic reticulum is studded with ribosomes.
![Mitochondria > <p>Intracellular membranes, e.g., those associated with mitochondria, also possess a structure and appearance similar to the plasma membrane. Mitochondria possess two membranes.</p>](https://digitalhistology.org/wp-content/uploads/2017/05/C.S.M-5-4-ping.png)
Mitochondria >
Intracellular membranes, e.g., those associated with mitochondria, also possess a structure and appearance similar to the plasma membrane. Mitochondria possess two membranes.
![Intercellular space > <p>The intercellular space contains numerous cellular extensions.</p>](https://digitalhistology.org/wp-content/uploads/2017/05/C.S.M-5-5-ping.png)
Intercellular space >
The intercellular space contains numerous cellular extensions.
![Cellular extensions > <p>The intercellular space contains numerous cellular extensions.</p>](https://digitalhistology.org/wp-content/uploads/2017/05/C.S.M-5-6-ping.png)
Cellular extensions >
The intercellular space contains numerous cellular extensions.