Fig. 4
From: Regulation and evolution of muscle development in tunicates
Illustration adapted from Tokuoka et al. [329]
Cell lineages of the tail muscles of ascidian larvae. Diagram of primary and secondary tail muscle lineage development in two species, Halocynthia roretzi and Ciona robusta. Bottom row: tailbud stages of the two species showing divergent muscle cell contributions color-coded according to conserved lineages indicated in top row (which are identical between the two species). 8-cell and tailbud stage views are lateral, 64-cell and 110-cell views are vegetal. In Halocynthia, the b4.2 blastomeres contribute to 5 muscle cells on each side of the tail, descended from b8.17 and b8.19. In Ciona, the b4.2 blastomeres gives rise to only 2 muscle cells on each side, and only b8.17 is myogenic.