A binucleated 3T3 fibroblast remains relatively fixed in position as other fibroblasts migrate along its periphery through the extension and contraction of flattened lamellipodia and long, thin filopodia. The rapid appearance and disappearance of lamellipodia and filopodia that is demonstrated during high speed playback of time-lapse sequences appears to be similar to the flickering of a light, and is known as ruffling. The process occurs most frequently along the leading edge of a cell, as demonstrated by the dynamics of the 3T3 cells in this video.

Contact inhibition of fibroblast cells in culture can be observed as the 3T3 cells collide with the binucleated cell or each other. Ruffling ceases in the area of overlap, but continues in other regions of the cells. Eventually the repeated motions of surface extensions result in the separation of the briefly adjoined cells, and the freed fibroblasts take on new paths through the culture medium.

In the upper region of the field of view, a 3T3 fibroblast cell retracts all of its surface extensions and rounds up into a spherical geometry before undergoing mitosis. The two daughter cells appear to spin around in a brief dance as their surfaces develop numerous blebs and undergo various contortions before their cytoplasm flattens and the cells completely pull apart. The flattened fibroblasts resemble misshapen fried eggs, each with a rim of lamellipodia.