Figure 4
From: Myogenesis in the basal bilaterian Symsagittifera roscoffensis (Acoela)
Embryo on the third day (approx. 65 hours, 54% of development between egg deposition and hatching) with anterior facing upwards. A. On the ventral side, irregular muscles (double arrows) are visible between the muscle grid of the longitudinal (lm), circular (cm) and diagonal muscles (dm). B. Ventral view. C. Dorsal view. Circular muscles appear denser than longitudinal muscles. Scale bars: 50 μm.