Mirror symmetry of newly divided rat periodontal ligament fibroblasts in situ and its relationship to cell migration

A dramatic increase in proliferation of endothelial, paravascular cells, and PDL fibroblasts occurs during orthodontic tooth movement. The development of mirror symmetry in newly divided fibroblast daughter cell pairs in the rat periodontal ligament was studied. Periodontal ligament fibroblasts loose their polarity and the normal organization of their organelles during cell division. Daughter cells, however, regain polarity and organization of their organelles to form mirror images of each other within 10 hours after cell division starts. Cellular polarity begins to appear with projection of a distal cell process at late telophase. Polarization is completed between late telophase and cytokinesis by shifting the RER and Golgi complex from the cleavage plane area to a juxtanuclear position facing the distal cell process. The majority of the newly divided fibroblasts formed mirror images in orientation and organization of organelles prior to cell migration. The distal cell process is the leading edge; i.e., the nuclear‐Golgi axis points toward the direction of movement.