[Kinematics of fibroblast spreading. II. Individual locomotor activity]

An analysis of area changes of normal mouse fibroblasts during their spreading is made with time intervals of 5-50 s. A mean increase of the area takes place simultaneously with area fluctuations of various rhythms, which result from accidental undulations of the lamella edge. The fluctuations are also the same during intermediate temporary stopping of cell spreading. The central cell region--endoplasm--is stretched passively by centrifugal lamella forces and is an active antagonist of forces in squeeze processes. A description is made of the lamella edge undulations like the phase states change of protraction and retraction, and it is shown by two-dimensional phase diagrams that edge-activity has a zone organisation. These zones can migrate upon the cell perimeter as a wave in stohastic excitable medium.