Mitochondria consist of an outer membrane and a highly folded inner membrane and are generally tubular in shape.

• Mitochondria are usually not seen with the LM unless special stains or histochemical techniques are used.
• Histochemical staining here uses specific enzymes of the citric acid cycle, which are only found in mitochondria, to generate the color seen.

What can the number and location of mitochondria in a cell tell you about the cell’s function?

Less fundamentally important than the organelles mentioned so far, inclusions are cytoplasmic accumulations of various cell products which are not membrane-bound.

• Examples are lipid droplets, glycogen granules, and melanin granules
• Lipid requires special fixation and staining to be seen, glycogen usually requires a special stain, but melanin requires no stain.

The next unit deals with cell division and aopotosis.