A colony of LLC-MK2 rhesus monkey kidney epithelial cells migrates across the surface of an imaging chamber though the dynamics of the lamellipodia that extend along their free edges. Each lamellipodium chiefly consists of a complex, branched network of actin filaments located just beneath the plasma membrane in the cell’s cortex. Changes in shape reflect alterations in the polymerization and organization of the actin.

Most LLC-MK2 cells feature a single nucleus, but a binucleated cell is visible as the time-lapse sequence initiates. Some studies suggest that the division of binucleated cells often results in daughter cells that are aneuploid. The previously mentioned binucleated LLC-MK2 cell does not divide during the video, but a mononucleated cell can be observed dividing erratically to produce a binucleated daughter cell and a mononucleated daughter cell.

The small fragments of material that sporadically flow across the field of view are cell debris. The fragments, one of which is particularly large, are not adequately attached to the surface of the imaging chamber. Consequently, they are carried away from the substratum by currents in the culture medium. Intact LLC-MK2 cells are not swept away by the currents in the same manner because they maintain relatively strong junctions with the extracellular molecules covering the culture surface.