Pleuro-buccal projections in pulmonate molluscs

Area of Science:

• Neuroscience
• Molluscan Biology
• Comparative Neurology

Background:

• The central nervous system (CNS) of pulmonate snails and slugs exhibits complex neuronal circuitry.
• Understanding the homologous neuronal pathways across different species is crucial for evolutionary and functional insights.

Purpose of the Study:

• To identify and characterize neurons projecting to the cerebro-buccal connective in pulmonate gastropods.
• To investigate the presence of homologous neuronal structures across diverse freshwater and terrestrial species.

Main Methods:

• Nickel lysine axonal filling technique was employed to stain neurons in the CNS.
• Neuronal tracing was performed in multiple species of freshwater (Basommatophora) and terrestrial (Stylommatophora) pulmonates.

Main Results:

• A symmetrical, homologous pair of small neurons was consistently identified in the pleural ganglia of all examined species.
• These neurons exhibit a unique axonal trajectory, passing through the ipsilateral pedal ganglion en route to the cerebral ganglia.

Conclusions:

• The identified paired pleural neurons are proposed to be homologous across the studied pulmonate species.
• These neurons are hypothesized to play a role in the neural coordination of defensive withdrawal behaviors with feeding inhibition.