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Acta Parasitologica

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Volume 61, Issue 1


Fertilization in the cestode Echinococcus multilocularis (Cyclophyllidea, Taeniidae)

Zdzisław Świderski
  • Corresponding author
  • W. Stefański Institute of Parasitology, Polish Academy of Sciences, 51/55 Twarda Street, 00-818 Warszawa, Poland
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  • Other articles by this author:
  • De Gruyter OnlineGoogle Scholar
/ Jordi Miquel
  • Laboratori de Parasitologia, Departament de Microbiologia i Parasitologia Sanitàries, Facultat de Farmàcia, Universitat de Barcelona, Av. Joan XXIII, sn, 08028 Barcelona, Spain
  • Institut de Recerca de la Biodiversitat, Facultat de Biologia, Universitat de Barcelona, Av. Diagonal, 645, 08028 Barcelona, Spain
  • Other articles by this author:
  • De Gruyter OnlineGoogle Scholar
/ Samira Azzouz-Maache
  • Laboratoire de Parasitologie et Mycologie Médicale, Faculté de Pharmacie, Université Claude Bernard-Lyon 1, 8 Av. Rockefeller, 69373 Lyon Cedex 08, France
  • Other articles by this author:
  • De Gruyter OnlineGoogle Scholar
/ Anne-Françoise Pétavy
  • Laboratoire de Parasitologie et Mycologie Médicale, Faculté de Pharmacie, Université Claude Bernard-Lyon 1, 8 Av. Rockefeller, 69373 Lyon Cedex 08, France
  • Other articles by this author:
  • De Gruyter OnlineGoogle Scholar
Published Online: 2015-12-30 | DOI: https://doi.org/10.1515/ap-2016-0010


Fertilization in the taeniid cestode Echinococcus multilocularis with uniflagellate spermatozoa was examined by means of transmission electron microscopy (TEM). Fertilization in this species occurs in the oviduct lumen or in the fertilization canal proximal to the ootype, where the formation of the embryonic capsule precludes sperm contact with the oocytes. Cortical granules are not present in the cytoplasm of the oocytes of this species, however, several large bodies containing granular material where frequently observed. Spermatozoa coil spirally around the oocytes and syngamy occurs by lateral fusion of oocyte and sperm plasma membranes. In the ootype, one vitellocyte associates with fertilized oocyte, forming a membranous capsule which encloses both cell types. In this stage, the spirally coiled sperm body adheres partly to the external oocyte surface, and partially enters into the perinuclear cytoplasm. The electron-dense sperm nucleus becomes progressively electron-lucent within the oocyte cytoplasm after penetration. Simultaneously with chromatin decondensation, the elongated sperm pronucleus changes shape, forming a spherical male pronucleus, which attains the size of the female pronucleus. Cleavage begins immediately after pronuclear fusion.

Keywords : Echinococcus multilocularis; Taeniidae; Cestoda; fertilization; ultrastructure


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About the article

Received: 2015-07-06

Revised: 2015-09-11

Accepted: 2015-09-14

Published Online: 2015-12-30

Published in Print: 2016-01-01

Citation Information: Acta Parasitologica, Volume 61, Issue 1, Pages 84–92, ISSN (Online) 1896-1851, ISSN (Print) 1230-2821, DOI: https://doi.org/10.1515/ap-2016-0010.

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