The Madin-Darby bovine kidney epithelial cells exhibit pronounced contact inhibition of migration. Whenever one of the cells encounters another cell in its path, the two become stuck together and the ruffling of their lamellipodia ceases in the area of overlap. Lamellipodial activity may continue in other regions along the periphery of the cells and is sometimes strong enough to allow the cells to sever their bonds to one another and continue independent migration. More commonly, however, the cells continue to adhere to one another and travel across the culture surface together. As more and more cells collide with them, the colony of epithelial cells grows.

Notably only a small number of MDBK cells are present in the field of view at the beginning of this time-lapse sequence. Seven of the cells are organized into a colony, one of which attempts to break away from the group, but returns quickly with an elastic-like snap. Immediately after, the cell assumes the characteristic pre-mitotic spherical geometry and begins cell division. The conspicuous blebbing of the daughter cells ends as they settle on the culture medium and stretch out broad lamellipodia across the substratum.

The daughter cells assume distinct polarities and separate from each other to begin migrating along their own paths. Neither can travel far before they collide with and are incorporated into MDBK cell colonies. By the end of the time-lapse sequence, the increasing number of epithelial cell colonies have come together to form an almost contiguous monolayer of cells. Notice, when there is only a little open space left, the lamellipodia along the free margins of some of the cells assume the shape of nearby gaps, as if they were attempting to fill them in to complete the cell sheet.