Fig. 7

Myosin expression in the trunk and spinal cord. (A–C, E, G, and I) Side views with anterior to left. (D, F, H, and J) Cross-sections at levels indicated in (C, E, G, and I), respectively. (A) myo2hc2 is strongly expressed in the differentiating muscles of the somites (white arrowheads), but only weakly in the newly formed somites (black arrowhead). (B) myo18a is expressed in the mesenchyme of newly formed and differentiating somites (black arrowhead), and strongly in the cells at the boundaries of older somites (white arrowheads). (C and D) myo1b2 is expressed broadly in the trunk, excluding the presomitic mesoderm (C). Expressing cells are located superficially within the somitic mesoderm (arrowhead, D), and in the notochord (asterisk). (E and F) At 18 hpf, myo5a expression is restricted to the spinal cord at anterior trunk levels (E), and represents differentiating neurons (arrowhead, F). (G and H) At 30 hpf, myo5a is expressed by scattered cells located in the dorsal half of the spinal cord (G). A cross-section in the anterior trunk (H) shows that expressing cells include neurons (arrowhead) and migrating neural crest cells (arrows). (I and J) myo10a is expressed in a continuous column of cells in the dorsal half of the spinal cord (I), including neurons (arrowheads, J). Asterisks in (D, F, H, and J) indicate the notochord. Scale bar (I), 50 μm (A–C, E, G, and I). Scale bar (J), 50 μm (D, F, H, and J).