Cell and Tissue Research

, Volume 267, Issue 2, pp 357–364 | Cite as

Junctional complexes of the branchia and gut of the tunicate, Pyrosoma atlanticum (Pyrosomatida, Thaliacea)

  • P. Burighel
  • G. B. Martinucci
  • N. J. Lane
  • R. Dallai


The branchia of pyrosomes has been found to be like that of ascidians in that it shares with the latter, besides the presence of peribranchial chambers, stigmata bordered by clusters of seven rows of flattened cells, each bearing a single row of long cilia. The intercellular junctions between ciliated cells of the branchial basket and between the cells lining the gut, in pyrosomes, have been studied in thin sections and by freeze-fracture. In both tissues tight and gap junctions are present, but the former are much more extensive in the gut. The gap junctions in the branchial basket exhibit some atypical features. Moreover, although there are extensive zonulae adhaerentes between the ciliated cells of the branchial basket, there are none between the epithelial cells of the intestinal tract. This feature of the branchiae, together with the alignment of their cells into highly ordered rows of seven cells, are similar to those found in some groups of ascidians. The evolutionary relationships between pyrosomes and the aplousobranch ascidians are considered in the light of these results.

Key words

Branchial stigmata Gut Epithelium Cell junctions Pyrosomatida, Pyrosoma atlanticum (Tunicata) 


Unable to display preview. Download preview PDF.

Unable to display preview. Download preview PDF.


  1. Burighel P, Dallai R, Martinucci GB (1985) Scalariform junction in the gut of tunicates. Biol Cell 54:171–176Google Scholar
  2. Burighel P, Martinucci GB, Dallai R (1988) Membrane specializations in the alimentary tract of ascidians. In: Ghiara G (ed) Cell interaction and differentiation. University of Naples, pp 191–205Google Scholar
  3. Burighel P, Lane NJ, Martinucci GB, Fenaux R, Dallai R (1989) Junctional diversity in two regions of the epidermis of Oikopleura dioica (Tunicata, Larvacea). Cell Tissue Res 257:529–535Google Scholar
  4. Burighel P, Martinucci GB, Casagrande L (1990) Organizzazione dello stigma e specializzazioni ciliari nella branchia di Pyrosoma (Tunicata). Atti LIII Congr UZI, Palermo, p. 352Google Scholar
  5. Cavey MJ, Cloney RA (1972) Fine structure and differentiation in ascidian muscle. I. Differentiated caudal musculature of Distaplia occidentalis tadpoles. J Morphol 138:349–374Google Scholar
  6. Cavey MJ, Cloney RA (1976) Ultrastructure and differentiation of ascidian muscle. I. Caudal musculature of the larva Diplosoma macdonaldi. Cell Tissue Res 174:289–313Google Scholar
  7. Cavey MJ, Wood RL (1986) Intercellular junctions in the larval epidermis of the colonial ascidian Distaplia occidentalis: a thin section and freeze-fracture examination. Can J Zool 64:112–117Google Scholar
  8. Dallai R, Burighel P, Martinucci GB, Maci R, Camatini M (1989) Actin localization at the tight junctions of invertebrate ciliated epithelia. Tissue Cell 21:37–46Google Scholar
  9. Delage Y, Herouard E (1898) Traité de Zoologie Concrète, vol 8. Les Prochordés. Schleicher Frères, ParisGoogle Scholar
  10. Georges D (1979) Gap and tight junctions in tunicates: study in conventional and freeze-fracture techniques. Tissue Cell 11:781–792Google Scholar
  11. Green CR, Bergquist PR (1982) Phylogenetic relations within the invertebrata in relation to the structure of septate junctions and the development of “occluding” junctional types. J Cell Sci 53:279–305Google Scholar
  12. Holland LZ (1988) Spermatogenesis in the salps Thalia democratica and Cyclosalpa affinis (Tunicata: Thaliacea): an electron microscope study. J Morphol 198:189–204Google Scholar
  13. Holland LZ (1989) Fine structure of spermatids and sperm of dolioletta gegenbauri and Doliolum nationalis (Tunicata: Thaliacea): implications for tunicate phylogeny. Mar Biol 101:83–95Google Scholar
  14. Holland LZ (1990) Spermatogenesis in Pyrosoma atlanticum (Tunicata: Thaliacea: Pyrosomatida): implications for tunicate phylogeny. Mar Biol 105:451–470Google Scholar
  15. Lane NJ, Dallai R, Burighel P, Martinucci GB (1986) Tight and gap junctions in the intestinal tract of tunicates (Urochordata): a freeze-fracture study. J Cell Sci 84:1–17Google Scholar
  16. Lane NJ, Dallai R, Martinucci GB, Burighel P (1987) Cell junctions in Amphioxus (Cephalochordata). A thin section and freeze-fracture study. Tissue Cell 19:399–411Google Scholar
  17. Lorber V, Rayns DG (1972) Cellular junctions in the tunicate heart. J Cell Sci 10:211–227Google Scholar
  18. Martinucci GB, Dallai R, Burighel P (1987) A comparative study on ciliary differentiations in the branchial stigmata of ascidians. Tissue Cell 19:251–263Google Scholar
  19. Martinucci GB, Dallai R, Burighel P, Lane NJ (1988) Different functions of tight junctions in the ascidian branchial basket. Tissue Cell 20:119–132Google Scholar
  20. Martinucci GB, Burighel P, Dallai R, Lane NJ (1990) Unusual features of intercellular junctions in the larvacean Oikopleura dioica. Cell Tissue Res 260:299–305Google Scholar
  21. Oliphant LW, Cloney RA (1972) The ascidian myocardium: sarcoplasmic reticulum and excitation-contraction coupling. Z Zellforsch Mikrosk Anat 129:395–412Google Scholar
  22. Ritter W (1905) The pelagic Tunicata of the San Diego region, excepting the Larvacea. Univ Calif Publs Zool 2:51–112Google Scholar
  23. Tokioka T (1971) Phylogenetic speculation of the Tunicata. Publs Seto Mar Biol Lab 19:43–63Google Scholar
  24. Uljanin B (1884) Die Arten der Gattung Doliolum im Golfe von Neapel und den angrenzenden Meeresabschnitten. Fauna Flora Golf Neapel 10:1–140Google Scholar
  25. Van Soest RMW (1981) A monograph of the order Pyrosomatida (Tunicata, Thaliacea). J Plankton Res 3:603–631Google Scholar

Copyright information

© Springer-Verlag 1992

Authors and Affiliations

  • P. Burighel
    • 1
  • G. B. Martinucci
    • 1
  • N. J. Lane
    • 2
  • R. Dallai
    • 3
  1. 1.Department of BiologyUniversity of PaduaPaduaItaly
  2. 2.Department of ZoologyUniversity of CambridgeCambridgeUK
  3. 3.Department of evolutionary BiologyUniversity of SienaSienaItaly

Personalised recommendations