TEM cultured for 10 days without electrical stimulation. (a) Top and side views of the TEM are attached to the microforce measurement system. Silicone rubber rings were attached to the PTFE pillars so that the TEM would not be dropped. Due to cell-mediated gel compaction, the width and thickness of the TEM were reduced from 4 mm to 0.99 mm and 5 mm to 1.00 mm, respectively. (b) Representative twitch and tetanus contraction traces evoked by electrical pulses. (c) Declination of contractile force by repeated electrical stimulation. The force for each stimulation was shown as a ratio to the force for the first stimulation.