Fig. 9

Segmental organization of the brain and composition of anteriormost post-oral commissures in arthropods and onychophorans. Anterior is up. Post-oral commissures are numbered. a Condition in arthropods (modified from Fanenbruck et al. [1]). Note that the first post-oral commissure contains both deutocerebral (blue) and tritocerebral fibers (green). b Situation in Onychophora, as revealed in the present study. The first post-oral commissure is most likely associated with the deutocerebrum, whereas commissures #2 to #5 consist of both deutocerebral fibers (blue) and fibers associated with the anterior portion of nerve cords belonging to the slime papilla segment (green). an antenna, cc connecting cord, dc deutocerebrum, ey eye, nc nerve cord, pc protocerebrum, ph pharynx, jw jaw, sp slime papilla, st stomodeum, tc tritocerebrum