Retrograde tracing of motor neurons associated with leg nerves in the onychophoran Euperipatoides rowelli. (A) Diagram of expected, anteriorly shifted arrangement of neuronal cell bodies supplying the legs, if parasegments were present. (B) Diagram of revealed arrangement. Note that the neuronal cell bodies supplying the legs are not shifted anteriorly but lie next to the root of each leg nerve. (C, D) Retrograde fills of leg nerves with dextran coupled to tetramethylrhodamine in dissected nerve cords of the onychophoran Euperipatoides rowelli. Confocal micrographs. Note the position of neuronal cell bodies next to the roots of the leg nerves (arrowheads in D). Abbreviations: al, anterior leg nerve; pl, posterior leg nerve. Scale bars: 50 μm (C) and 250 μm (D).
Mayer et al. BMC Evolutionary Biology 2013 13:230 doi:10.1186/1471-2148-13-230