Figure 3.

Myoanatomy of an Early Larva and an Early Postmetamorphic Individual of Wirenia argentea

Scale bars represent 20 μm in (A) and (B) and 100 μm in (F). Apical is up in all panels except (E), which is a cross-section. (A), (B), and (F) are maximum-intensity (MI) z projections of confocal image stacks. For better visualization of the individual muscle systems, only the regions indicated in (E) were used in the MI z projections shown in (A) and (B). (C)–(E) are schematic representations of the musculature in the early-stage larva.

(A) Dorsal third of the larva with early anlage of the prototroch muscle ring (ptr) and enrolling muscle (em). sp, unspecific signal from epidermal spicule-secreting cells.

(B) Ventral region with the paired ventrolateral muscle (vlm) and the first seven pairs of myocytes (arrowheads) of the dorsoventral musculature.

(C) Dorsally positioned musculature seen from ventral.

(D) Ventrally positioned musculature seen from dorsal.

(E) Cross-section with all muscle systems of the early larva.

(F) Ventrolateral view of a postmetamorphic individual caught in the field, showing the body wall musculature (bwm) and the multiple sets of dorsoventral muscles (arrowheads), as well as the mouth (m), pedal pit (pp), and pedal groove (pg).