Fig. 7. Differential traction forces during cellular alignment as a result of a 10-V/cm electric field in a primary bovine osteoblast on a substrate with a stiffness of 6000 N/m². +/– labeled scale vectors indicate orientation of the electric field. A, the phase of increasing force. After 5 minutes (E and F) the loss of the normally inward-pulling traction forces occur at sides where the cell will start to elongate a few minutes later (d and e). The bar scale represents 10 µm; the scale vector represents 10 N/m². Retraction between E and F is visible at area labeled a and b.