Nervous system and morphology of three species of Nemertodermatida (Acoelomorpha) as revealed by immunostainings, phalloidin staining, confocal and differential contrast microscopy
(English)Manuscript (preprint) (Other academic)
Nemertodermatida are microscopic marine worms likely to be the sister-group to acoels and the earliest extant bilaterian animals. The nervous system of Flagellophora apelti, Sterreria sp. and Nemertoderma westbladi has been investigated by immunohistochemistry and confocal microscopy using anti-tubulin, anti-5-HT and anti-FMFRamide antibodies as well as by phalloidin staining.
The nervous system of Flagellophora apelti is composed of a large brain neuropile at the level of the statocysts with several fibres surrounding it and innervating the broom organ. Sterreria sp. shows a commissural-like brain and several nerve cords going frontad and caudad from this. At the level of the statocysts there is also a thicker aggregation of IR fibres. The nervous system of N. westbladi consists of a nerve ring lying outside the body wall musculature at the level of the statocyst and a pair of ventro-lateral nerve cords, from which extend numerous fibres innervating the ventral side of the animal. Numerous bottle-shaped glands were observed, innervated by fibres starting both from the brain and the cords. Those nemertodermatids studied to-date display no common nervous system pattern. This study demonstrates that the nemertodermatid nervous system possesses a number of plesiomorphic features and appears more primitive than the nervous system in other worms, except Xenoturbellida. The musculature of Sterreria sp., as revealed by phalloidin-TRITC staining, shows diagonal muscles in the anterior quarter of the body and a simple orthogonal grid in the posterior three quarters. It is more primitive than that of the other nemertodermatids. High-resolution differential contrast microscopy permitted to better visualise some morphological characters such as statocysts, sperm and glands.
Flagellophora apelti, Sterreria sp., Nemertoderma westbladi, Nemertodermatida, nervous system, immunocytochemistry, musculature, statocyst, broom organ, bottle-shaped glands, sperm
Zoology Biological Systematics
Research subject Zoology; Molecular Biology; Systematic Zoology
IdentifiersURN: urn:nbn:se:su:diva-107588OAI: oai:DiVA.org:su-107588DiVA: diva2:748751
FunderSwedish Research Council, 2012-3913