Objective: UPlanSApo 100x oil/1.40	Exposure: 400 ms
Microscope: Olympus DSU/IX81	Gain: 3
Camera: Hamamatsu ImagEM	Interval: 2 s

Mitochondria are often depicted as static, cylinder-shaped organelles, but time-lapse studies reveal that the important energy generators may change shape and move about the cytoplasm on an almost continuous basis. These activities often appear to involve the cytoskeletal microtubules, which influence the characteristic direction and dissemination of the mitochondria in various kinds of cells. The number of mitochondria present in a cell is related to the metabolic needs of that cell, and may range from a single large mitochondrion to thousands of the organelles. Their size generally ranges from 1 to 10 micrometers, making mitochondria large enough to be observed with a light microscope. The organelles were originally identified during the 1800s, and were commonly believed to transmit hereditary information until after the beginning of the twentieth century. Most of the modern understanding of the functional role of mitochondria did not develop until after a method for isolating the intact organelles was developed in 1948. In the digital video presented above, normal Gray fox lung fibroblast cells (FoLu line) are expressing monomeric green fluorescent protein (mEGFP) fused to the mitochondrial targeting signal from subunit VIII of human cytochrome C oxidase.