Figure 9

Brain and muscle development of P. dumerilii , 24-30 hpf, apical view, dorsal side up. The age of the larvae in each row is given in the lower left corner of the first picture of each row. The displayed staining is indicated at the bottom of each column. A, F, K, P: The dorsal root of the circumesophageal connectives (drcc) is visible at 24 hpf as well as the developing prototroch ring nerve (ptrn). From 26 hpf onwards the ventral branch of the circumesophageal connectives (vrcc) and the unpaired dorsal axon (ua) are visible. The dorsal and ventral roots of the circumesophageal connectives connect the cerebral commissures (cc) in the brain. The prototroch ring nerve becomes more pronounced. B, G, L: The first serotonergic cell (white star) is located in the apical organ just below the apical tuft (apt). Q: At 30 hpf a second serotonergic cell appears (white arrow). C, D, H, I, M, N, R, S: From 28 hpf onwards the dorsal longitudinal muscles (dlm) become visible. E, J, O, T: The amount of cells in the brain is increasing. CLSM microscopy, maximum projection, Imaris surpass mode. Scale bar in all images 20 μm. Further abbreviations see abbreviations list.