Because mitochondria are rod shaped and only 0.1 to 0.2 µm in diameter, they are at the resolution limit of a light microscope. However, mitochondria were described by staining with iron hematoxylin many years before they were studied by electron microscopy. Today, this technique is primarily of historical interest because of the availability of mitochondria-specific vital dyes and antibodies.
Mitochondria can be distinguished as darkly stained, thread-like structures in the apical cytoplasm of some cells. They appear as dark grey lines that run parallel to the long axis of the cell and perpendicular to the cell surface.
The Golgi apparatus is visible as an unstained region adjacent to the nucleus.
These cells are polarized with their basal surface resting on the underlying connective tissue while the apical surface faces the lumen.
The liver is composed primarily of hepatocytes. Examine individual hepatocytes at high magnification.
The cytoplasm is filled with so many mitochondria that it is difficult to distinguish them individually. The mitochondria are thread-like or granular depending on their orientation.
Although the nucleus does not stain, the nucleolus is prominently stained. Some of the cells have more than one nucleolus.