Figure 9

Late embryonic development of the nervous and muscle systems in Maritigrella crozieri. CLSM micrographs of fluorescently labeled wholemounts from 71-100% development time (phalloidin - white, 5HT - magenta, acTub - green, FMRFamide - blue). (A) Ventro-left lateral view showing acTub and FMRFamide immunoreactivity in the cerebral commissure (cc), intraepithelial nerves (ien) and dorso-lateral connective (dlc). AcTub expression is also in the protonephridia (pnp) and in cilia in the pharynx (ph). (B) Ventral view showing circular muscle formation around the mouth (double arrowhead) and 5HT expression in the pharyngeal nerve ring (phnr) with its bilaterally symmetric perikarya (php). Two nerves extend posteriorly from the pharyngeal nerve ring and converge at a ventral perikarya (vp) before joining the dorso-lateral connective with it's caudal perikaya (cp). Myofibrils diverge from the orthogonal muscle grid as lobe formation commences, a circular muscle loops over the oral hood (arrowhead). (C) Left lateral view 10 hours before hatching showing areas of double muscle fibers (arrowhead), flattened circular muscles (double arrowheads) and circular nerves of the dorsal plexus (asterisks) following the anterior primary circular muscles (apcm). Scale bars 100 μm.