The serotonin-positive neurons in the suboesophageal ganglion send most processes into the neuropil, where they form a few thick fibre tracts.

• 背叶、后脑和咽下神经节的着色也非常强烈，咽下神经节周围的阳性胞体发出纤维到咽下神经节，并在咽下神经节内形成几条粗大的纤维。