An imaging chamber is filled with a high volume of raccoon uterus cells so that the fibroblasts are often forced to crawl over other cells in order to continue migrating. The activity of many of the cells appears, however, to be somewhat inhibited by the numerous contacts they have formed with neighboring fibroblasts. Notice, along overlapping cell margins the ruffling lamellipodia that are heavily utilized in fibroblast locomotion are conspicuously absent. The characteristic lamellipodial behavior is only observable at points along the peripheries of the cells that are free from cell-cell contacts.

The number of cells in the crowded chamber appears to increase over the course of the time-lapse sequence, several PL 1 Ut fibroblasts successfully undergoing mitosis. After the parent cells retract their surface protrusions and assume roughly spherical geometries, material can be seen aligned along the equators of the cells. Though individual chromosomes cannot be detected, the equatorial ridges presumably signify that the metaphase plate has been formed. Soon after, there is a sudden rift midway through the material as replicated pairs of chromosomes are pulled apart with the abrupt commencement of anaphase. A cleavage furrow is formed and cytokinesis is completed, producing a pair of daughter cells that develop their own polarities and begin migrating in disparate directions.

Cell debris can be periodically observed flowing from the top of the field of view to the bottom, appearing reminiscent of falling snow. The material, which usually results from the fragmentation of dead cells or the severing of adhesions with the substratum by migrating cells that are unable to release them in any other manner, is carried by currents in the culture medium. The currents are capable of lifting the cell fragments, but not intact PL 1 Ut cells, away from the surface of the imaging chamber because of the strong junctions called focal adhesions fibroblasts tend to form with molecules along the substratum.