Transmission EMs Show the Post-Replating Progression of CPS Cells

<div><p>(A) Round, day 3 cells contain disordered myosin filaments. Some of these cells beat while still floating (see <a href="http://www.plosbiology.org/article/info:doi/10.1371/journal.pbio.0030087#sv001" target="_blank">Video S1</a>) and typically have APs as shown in <a href="http://www.plosbiology.org/article/info:doi/10.1371/journal.pbio.0030087#pbio-0030087-g006" target="_blank">Figure 6</a>A.</p> <p>(B) Upper box is a blowup taken from lower panel, showing myosin filaments of characteristic 1.6-μm length radiating outward from dense body.</p> <p>(C) Day 14 cell with a single, central nucleus shows a stretching out of the dense bodies into an organizing sarcomere.</p> <p>(D) Day 3 round cells containing copious mitochondria (inset).</p> <p>(E) Elongated day 7 cell containing a dense body (arrowhead).</p> <p>(F) Uninucleate day 14 cell, same cell as in (C).</p> <p>(G) By day 56, a well-defined sarcomere is present, with identifiable A- and I-bands and M- and Z-lines.</p> <p>(H) Sarcomere from a fetal cardiomyocyte is shown for comparison.</p>