Quantifying Myotome Growth in Zebrafish

Bright-field and wide-field fluorescence imaging was performed under a Leica MZ16F with Imaging Development Systems Gmbh iDS camera. For confocal imaging, larvae were mounted in 0.8 to 1% low melting point agarose, and data were collected on the somites 17 and 18 near the anal vent on a Zeiss LSM 5 Exciter microscope equipped with 20×/1.0W objective and subsequently processed using either Volocity 6.3 (Perkin-Elmer), Fiji (NIH), or ZEN (Zeiss) software. For live imaging, mounted larvae were transiently anesthetized with tricaine. Immediately after the scan, larvae were washed and then separately housed in 24-well or 96-well plates to track individual myotome growth. Medium in each well was changed every 12 h. Myotome volume was calculated as described (19 (link), 20 (link)) and schematized in SI Appendix, Figs. S1A and S9A.