nerve cord

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nerve cord

a strand of nervous tissue that forms part of the CENTRAL NERVOUS SYSTEM of invertebrates.
References in periodicals archive ?
The most important of these are the evolution of segmentation at the base of the annelid-cchiuran-sipunculan line, multiplication and fusion of the ventral nerve cords in several annelid/echiuran taxa as well as in the sipunculans, the secondary loss of segmentation in Sipun-cula, and the evolution of tetraneury and a complex apical organ with eight to ten central flask cells and a number of peripheral cells in the Tetraneuralia (entoprocts and molluscs) (Fig.
A recent study on sipunculan neurogenesis revealed that the larvae of this taxon undergo cryptic segmentation by forming a paired ventral nerve cord with associated, subsequently appearing, segmental commissures and four pairs of perikarya (Kristof et al., 2008; Wanninger et al., 2009; Fig.4D).
As the juveniles developed, strong IR was evident in the circumoral nerve ring and radial nerve cords, and the pattern of synaptotagmin localization reflected the histological organization of the asteroid CNS into the ectoneural and hyponeural tissue layers (Fig.
In both juveniles and adults, synaptotagmin localizes to the circumoral nerve ring and radial nerve cords, and its distribution reflects the histological organization of the sea star CNS.
Paraxial nerve cords merge with the nerve nodule near the pyriform complex (Fig.
The nervous system of both Bugula stolonifera and Bugula neritina consists of ciliated ray cells, neural plate cells, paraxial nerve cords, a nerve nodule, and a coronal nerve ring (Fig.
Notable features in the ventral and lateral nerve cords are some large, distinct ganglionic masses with ovoid neuropils in the head region (Fig.
Tracts from the neuropil compartments connect to a thick commissure that extends to the ventral and lateral nerve cords and cerebro-buccal connectives.
In leeches, intersegmental coordination is maintained with severed nerve cords (Yu et al., 1999), because feedback from stretch receptors in the body wall controls the segmental central pattern generators that produce the undulation rhythm (see Friesen and Cang, 2001).
Basal genera often have multiple, separate nerve cords (4 in Dactylopodola), whereas more derived genera show partial fusion of nerve cords (4 fuse into 2 in Turbanella) or presumably complete fusion (2 in Thaumastodermatidae).
Nerve cords were removed from ice-anesthetized adult lobsters and pinned out in lobster saline as previously described (Otsuka et al., 1967; Harris-Warrick and Kravitz, 1984; Ma et al., 1992).
The ventral exoskeleton was detached and removed to expose the ventral nerve cord. The blood vessels and connective tissue were carefully removed, leaving the isolated nerve cord.