This material is from the 4th edition of The Zebrafish Book. The 5th edition is available in print and within the ZFIN Protocol Wiki.
Fig 19. Demonstration with lineage tracer that somite 3 makes myotome 3. The images combine fluorescence due tintracellularly injected rhodamine-dextran and bright field (see Schilling and Kimmel, 1994, for method). The labeled cell in somite 3 (injected with lineage tracer at the 5-somite stage in A) differentiates into an elongated muscle fiber spanning myotome 3 (at the protruding-mouth stage in B). The white arrowheads in both panels show the posterior borders of somites (myotomes) 1 and 2.

Figure 19