Figure 25
From: Invertebrate neurophylogeny: suggested terms and definitions for a neuroanatomical glossary

Orthogon. A. Longitudinal and circular neurites (or neurite bundles) form an orthogon in the trunk of Tubiluchus troglodytes (Priapulida). The ventral neurite bundle is distinctly thicker and therefore called ventral longitudinal nerve cord. [Serotonin-like immunoreactivity.] B. Schematic representation of the orthogon. Abbreviations: cne = circular neurites; lne = longitudinal neurites; vlnc = ventral longitudinal nerve cord. A: Original: Schmidt-Rhaesa; B: From [222], with permission of Oxford University Press.