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Ultrastructure of potential photoreceptor organs in the larva ofScrupocellaria bertholetti (bryozoa)

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Summary

Pigmented spots have been implicated as potential photoreceptors in many bryozoan larvae which display phototactic behavior. Larvae ofScrupocellaria bertholetti, initially photopositive on release from the brood chambers, have a pair of identical posterolateral pigmented spots and a third morphologically different spot in the anteromedian line. The presumed photoreceptoral organelle in each is composed of numerous unmodified cilia which have the typical 9+2 arrangement of microtubules with electron-dense arms extending from thea-microtubule of each peripheral pair. The posterolateral pigmented spot is composed of two modified coronal cells and a basal sensory cell. Cilia arising from the apical part of this basal cell are aligned vertically. Densely packed pigment vesicles in the three cells form a shield that restricts light entry to one direction. The anteromedian pigmented spot is composed of four cells, two lateral and two posterior. Cilia of the opposing lateral cells are horizontally aligned, whereas cilia of the posterior cells are vertical and curve outward from the oral margin of the pigmented spot. Pigment vesicles are present in all four cells to form a complete shield. Extensions of the larval nervous system are in direct contact with the four cells of the anteromedian spot and the basal cells of the posterolateral spots. The posterolateral pigmented spots share structural and topological similarities with the pigmented spots ofBugula neritina, the only other supposed photoreceptors in lophophorates which have been studied at the ultrastructural level. It is not yet possible to homologize these potential photoreceptors with those of other groups.

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References

  • Eakin, R.M.: Lines of evolution of photoreceptors. In: General physiology of cell specialization (D. Mazia, A. Tyler, eds.), pp. 393–425. New York-San Francisco-Toronto-London: McGraw-Hill 1963

    Google Scholar 

  • Eakin, R.M.: Evolution of photoreceptors. Cold Spring Harbor Symp. Quant. Biol.30, 363–370 (1965)

    Google Scholar 

  • Eakin, R.M.: Evolution of photoreceptors. In: Evolutionary biology, Vol. 2 (Th. Dobzhansky, M.K. Hecht, W.C. Steere, eds.). pp. 194–242. New York: Appleton-Century-Crofts 1968

    Google Scholar 

  • Eakin, R.M., Martin, G.C., Reed, C.T.: Evolutionary significance of fine structure of archiannelid eyes. Zoomorphologie88, 1–18 (1977)

    Google Scholar 

  • Ermak, T.H., Eakin, R.M.: Fine structure of the cerebral and pygidial ocelli inChone ecaudata (Polychaeta: Sabellidae). J. Ultrastructure Res.54, 243–260 (1976)

    Google Scholar 

  • Lutaud, G.: Premiers stades de la croissance zoariale chez le Bryozoaire CheilostomeScrupocellaria reptans Thompson. Arch. Zool. Exptl. Gen.90, 42–58 (1953)

    Google Scholar 

  • Nielsen, C.: Phylogenetic considerations: the protostomian relationship. In: Biology of bryozoans (R.M. Woollacott, R.L. Zimmer, eds.), pp. 519–534. New York-London: Academic Press 1977

    Google Scholar 

  • Rosen, M.D., Stasek, C.R., Hermans, C.O.: The ultrastructure and evolutionary significance of the cerebral ocelli ofMytilus edulis, the Bay Mussel. The Veliger21, 10–19 (1978)

    Google Scholar 

  • Ryland, J.S.: Experiments on the influence of light on the behaviour of polyzoan larvae. J. Exptl. Biol.37, 783–800 (1960)

    Google Scholar 

  • Ryland, J.S.: Taxes and tropisms of bryozoans. In: Biology of bryozoans (R.M. Woollacott, R.L. Zimmer, eds.), pp. 411–436. New York-London: Academic Press 1977

    Google Scholar 

  • Siewing, R.: Probleme und neuere Erkenntnisse in der Grossystematik der Wirbellosen. Verh. Dt. Zool. Ges.69, 59–83 (1976)

    Google Scholar 

  • Woollacott, R.M., Zimmer, R.L.: Fine structure of a potential photoreceptor organ in the larva ofBugula neritina (Bryozoa). Z. Zellforsch. Mikr. Anat.123, 458–563 (1972)

    Google Scholar 

  • Woollacott, R.M., Zimmer, R.L.: Metamorphosis of cellularioid bryozoans. In: Settlement and metamorphosis of marine invertebrate larvae (F.-S. Chia, M.E. Rice, eds.), pp. 49–63. New York: Elsevier North-Holland 1978

    Google Scholar 

  • Zimmer, R.L.: Morphological and developmental affinities of the lophophorates. In: Living and fossil Bryozoa (G.P. Larwood, ed.), pp. 593–599. New York-London: Academic Press 1973

    Google Scholar 

  • Zimmer, R.L., Woollacott, R.M.: Structure and classification of gymnolaemate larvae. In: Biology of bryozoans (R.M. Woollacott, R.L. Zimmer, eds.), pp. 43–89. New York-London: Academic Press 1977

    Google Scholar 

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Authors and Affiliations

  1. Museum of Comparative Zoology, Harvard University, 02138, Cambridge, MA, USA

    Roy L. Hughes Jr. & Robert M. Woollacott

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  1. Roy L. Hughes Jr.
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  2. Robert M. Woollacott
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Hughes, R.L., Woollacott, R.M. Ultrastructure of potential photoreceptor organs in the larva ofScrupocellaria bertholetti (bryozoa). Zoomorphologie 91, 225–234 (1978). https://doi.org/10.1007/BF00999812

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  • DOI: https://doi.org/10.1007/BF00999812

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