Daughter 3T3 cells. Are they mirror images of each other?

Using a new technique to visualize the tracks of moving 3T3 cells and combining it with the visualization of actin containing microfilament bundles by indirect immunofluorescence experiments are presented which suggest that: 30-40% of the pairs of daughter 3T3 mouse fibroblasts in noncloned cultures have mirror symmetrical actin bundle patterns; the angle between separating daughter cells is approx. 90° or 180° and seems related to the directions of certain actin containing bundles; and approx. 40% of separately moving daughter cells which did not collide with any other cell in the culture, performed directional changes in a mirror symmetrical way. Both daughter cells entered the next mitosis at approximately the same time. It is suggested that the actin bundle pattern, the angle of separation, the major directional changes during interphase, and the time of the next mitosis are predetermined by the parental cell.