An example of localization of mitochondria in close proximity to a source of substrate is seen in the relationship of mitrochondria to lipid droplets. They may partially surround small lipid droplets and when the droplets are very large, as in this liver cell from a fasted hamster, several mitochondria may be closely applied to its surface. The fatty acid oxidases of the mitochondria are involved in the metabolism of triglycerides, and this intimate relationship no doubt facilitates transport of substrate to the enzymes.