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Basiepidermal nervous system in Nemertoderma westbladi (Nemertodermatida): GYIRFamide immunoreactivity
Olga I Raikova1, Maria Reuter, Margaretha K S Gustafsson
1Zoological Institute, Russian Academy of Sciences, St Petersburg, Russia.
Zoology (Jena, Germany)
|December 15, 2005
Summary
The nervous system of Nemertoderma westbladi, an early bilaterian animal, is a simple, basiepidermal nerve net. This primitive nervous system lacks a centralized brain and stomatogastric system, offering clues to the earliest animal nervous system organization.
Area of Science:
- Marine biology
- Evolutionary biology
- Neuroscience
Background:
- Nemertodermatida are microscopic marine worms, potentially the earliest extant bilaterian animals.
- Understanding the nervous system (NS) of the bilaterian ancestor is crucial for evolutionary studies.
Purpose of the Study:
- Investigate the nervous system of Nemertoderma westbladi to infer ancestral bilaterian NS characteristics.
- Determine the NS organization, including centralization and innervation patterns.
Main Methods:
- Indirect immunofluorescence technique and confocal scanning laser microscopy.
- Utilized antibodies against GYIRFamide and serotonin, alongside phalloidin-TRITC staining.
Main Results:
- An entirely basiepidermal NS was revealed, with a ring-like structure near the statocyst as the sole centralization ('brain').
- No stomatogastric NS was observed. Peptidergic and aminergic NS patterns showed distinct dorsal and ventral distributions.
- A pair of GYIRFamide immunoreactive nerve cords innervated the ventral side, mouth, and male genital opening.
Conclusions:
- The nemertodermatid NS exhibits plesiomorphic (ancestral) features, appearing more primitive than other studied worms.
- The bilaterian ancestor likely had a basiepidermal nerve net without centralized brain structures or a stomatogastric NS.