The saltatory movement of mitochondria and other organelles in RK13 cells can be observed during this live cell digital video. Coined from the Latin term saltus, meaning “jump,” saltations are episodic jumps of movement that are repeatedly interrupted by periods of rest. The organelles of both plant and animal cells move in saltations. In flattened cells settled on the substratum of a culture chamber, saltatory movement is usually directed either toward or away from the cell center, often along the intracellular microtubule network.

In addition to the typical organelles, some of the RK13 cells appearing in the digital video clearly contain large vacuoles. The vacuoles that form along the periphery of a rabbit kidney cell located in the bottom left-hand corner of the field of view are particularly prominent. In animal cells, vacuoles are primarily utilized as a means of temporary storage and transport for various materials, such as food, water, and wastes. Since the observable vacuoles form along cell margins through endocytosis, they presumably contain small segments of culture medium, which the cells digest to obtain essential nutrients. Notice, the vacuoles break down and disappear as they travel toward the center of the cells.

Lamellipodia are utilized by epithelial cells to locomote and are comprised of sheets of membrane-enclosed cytoplasm. Extension of lamellipodia over a substratum occurs in a fluid fashion. The surface structures are repeatedly pulled up from the substratum and flow backward into the cell as part of a complex phenomenon commonly termed ruffling. The ruffling of live cells can produce a flickering sensation during the high speed playback of time-lapse sequences.