Expression of Phox2 and Mnx in the subesophageal and stellate ganglia of Sepia officinalis . (a-f) Consecutive sagittal sections through the subesophageal ganglonic mass (a-c) or a stellate ganglion (d-f) hybridized with the indicated probes. Synaptotagmin 1/2/5 (So-Syt) is used as a pan-neuronal marker (a,d and Additional file 1: Figure S1f). Apart from the expressions described in the text, the brachial ganglion contains So-Mnx+ neurons, in line with its role in movement of the arms, but also So-Phox2+ neurons in its posterior wall, whose function has not been described so far. (g) Drawing, reproduced with permission from Figure thirteen of reference , showing the way in which the axons of stellate ganglion neurons progressively fuse to form the third order giant fibers (gf3) that allow jet-propulsion. (h) Schematic of the central nervous system and stellate ganglion of Sepia. br, brachial ganglion; D, dorsal; P, posterior; pa, anterior pedal ganglion; pp, posterior pedal ganglion; pv, palliovisceral ganglion; so, supraesophageal mass; st, stellate ganglion. Scale bars, 500 μm (a-c); 200 μm (d-f).