- Published:
Ultrastructural investigation of the nuchal organs ofPygospio elegans (Polychaeta). I. Larval nuchal organs
Helgoländer Meeresuntersuchungen volume 40, pages 397–417 (1986)
Abstract
The structural differentiation of the nuchal organs during the post-embryonic development ofPygospio elegans is described. The sensory organs are composed of two cell types: ciliated cells and bipolar primary sensory cells, constituting the nuchal ganglion, which is associated with both the sensory epithelium and the brain. Since the sensory neurons are largely integrated into posterolateral parts of the cerebral ganglion, the nuchal organs are primary presegmental structures. The microvilli of the ciliated cells form a cover over the cuticle with a presumed protective function. An extracellular space extends between cuticle and sensory epithelium. The distal dendrites of the sensory cells terminate in sensory bulbs, bearing one modified sensory cilium each that projects into the olfactory chamber, embedded within the secretion of the ciliated cells. During development, the nuchal organs increase in size. This is accompanied by a shift in position, an expansion of the sensory area, and secretory activity of the ciliated cells. The nuchal ganglion differentiates into three nuchal centres forming three distinct sensory areas around the ciliated region. Each nuchal complex reveals two short nuchal nerves comprising the sensory axons, which enter the posterior circumesophageal connective. The sensory cells lying in the brain exhibit neurosecretory activity; the sensory cilia enlarge their surface area by dilating and branching. Nuchal organs accomplish the basic structural adaptions of chemoreceptors and show structural analogies to arthropod olfactory sensilla; thus, there is every reason to suppose chemoreceptor function.
Literature cited
Åkesson, B., 1967a. The embryology of the polychaeteEunice kobiensis. — Acta zool., Stockh.48 142–192.
Åkesson, B., 1967b. On the nervous system of theLopadorhynchus larva (Polychaeta). — Ark. Zool.20 55–78.
Altner, H. & Prillinger, L., 1980. Ultrastructure of invertrebrate chemo-, thermo-, and hygroreceptors and its functional significance. — Int. Rev. Cytol.67 69–140.
Barber, V. C., 1974. Cilia in sense organs. In: Cilia and flagella. Ed. by M. A. Sleigh. Acad. Press, London, 403–433.
Bubel, A., 1983. A transmission and scanning electron microscopy study of the cuticle and epidermis ofPomatoceros lamarckii (Polychaeta: Serpulidae). — Trans. zool. Soc. Lond.36 217–268.
Bullock, T. H. & Horridge, G. A., 1965. Structure and function in the nervous system of invertebrates. Freemann, San Francisco1 1–750.
Clark, R. B., 1969. Systematics and phylogeny: Annelida, Echiura, Spunculida. — Chem. Zool.4 14.
Dhainaut-Courtois, N., 1968. Étude histologique et ulstrastructurale des cellules nerveuses du ganglion cérébral deNereis pelagica L. (Annélide, Polychète). — Gen. comp. Endocr.11 414–443.
Franke, W. W., Krien, S. & Brown, R. M. Jr., 1969. Simultaneous glutaraldehyde-osmium tetroxide fixation with postosmication. — Histochemie19 162–164.
Golding, D. W., 1973. Neuroendocrine phenomena in aphroditid and related polychaetes. 1. The morphology and cytology of the infracerebral gland and cerebral neurosecretory system. — Acta zool., Stockh.54 101–120.
Gustafson, G., 1930. Anatomische Studien über die Polychaetenfamilien Amphinomidae und Euphrosynidae. — Zool. Bidr. Uppsala12, 305–471.
Korn, H., 1982. Annelida. Morphogenese der Tiere. Fischer, Stuttgart, 166 pp.
Laverack, M. S., 1968. On the receptors of marine invertebrates. — Oceanogr. mar. Biol.6, 249–324.
Laverack, M. S., 1974. The structure and function of chemoreceptor cells. In: Chemoreception in marine organisms. Ed. by P. T. Grant & A. M. Mackie. Acad. Press, London, 48 pp.
Merker, G. & Vaupel-von Harnack, M., 1967. Zur Feinstruktur des „Gehirns“ und der Sinnesorgane vonProtodrilus rubropharyngaeus Jaegersten (Archiannelida). — Z. Zellforsch. mikrosk. Anat.81, 221–239.
Rullier, F., 1950. Rôle de l'organe nucal des annélides polychètes. — Bull. Soc. zool. Fr.75, 18–24.
Rullier, F., 1951. Étude morphologique, histologique et physiologique de l'organe nucal chez les annélides polychètes sédentaires. — Annls Inst. océanogr. Monaco25, 207–341.
Söderström, A., 1920. Studien über die Polychätenfamilie Spionidae. Diss., Univ. Uppsala, 101 pp.
Söderström, A., 1930. Über segmental wiederholte Nuchalorgane bei Polychäten. — Zool. Bidr. Uppsala12, 1–25.
Storch, V. & Welsch, U., 1969. Zur Feinstruktur des Nuchalorgans vonEurythoe complanata (Pallas), (Amphinomidae, Polychaeta). — Z. Zellforsch. mikrosk. Anat.100, 411–420.
West, D. L., 1978. Comparative ultrastructure of juvenile and adult nuchal organs of an annelid (Polychaeta: Opheliidae). — Tissue & Cell10, 243–257.
Whittle, A. C. & Zahid, Z. R., 1974. Fine structure of nuchal organs in some errant polychaetous annelids. — J. Morph.144, 167–184.
Author information
Authors and Affiliations
Rights and permissions
About this article
Cite this article
Schlötzer-Schrehardt, U. Ultrastructural investigation of the nuchal organs ofPygospio elegans (Polychaeta). I. Larval nuchal organs. Helgolander Meeresunters 40, 397–417 (1986). https://doi.org/10.1007/BF01983820
Issue Date:
DOI: https://doi.org/10.1007/BF01983820