Affordable Access

deepdyve-link
Publisher Website

Ultrastructure of the ovary and oogenesis in the flatworm Prosthiostomum siphunculus (Polycladida, Cotylea).

Authors
  • Gammoudi, Mehrez1
  • Salvenmoser, Willi2
  • Tekaya, Saïda1
  • Egger, Bernhard3
  • 1 Université de Tunis El manar, Faculté des Sciences de Tunis, UR11ES12 Biologie de la reproduction et du Développement animal, 2092 El Manar Tunis, Tunisia.
  • 2 Research Unit Evolutionary Developmental Biology, Institute of Zoology, University of Innsbruck, Technikerstr. 25, 6020, Innsbruck, Austria.
  • 3 Research Unit Evolutionary Developmental Biology, Institute of Zoology, University of Innsbruck, Technikerstr. 25, 6020, Innsbruck, Austria. [email protected]
Type
Published Article
Journal
Cell Biology International
Publisher
Wiley (John Wiley & Sons)
Publication Date
November 2016
Volume
40
Issue
11
Pages
1174–1186
Identifiers
DOI: 10.1002/cbin.10657
PMID: 27542977
Source
Medline
Keywords
License
Unknown

Abstract

Based on light and electron microscopy observations, oogenesis in the cotylean polyclad Prosthiostomum siphunculus was investigated for the first time. The numerous ovarian follicles are dispersed essentially in the dorsal parenchyma. In the follicles, a ventral germinative zone with undifferentiated germs cells of different sizes and a dorsal growth zone with larger growing and abortive oocytes are present. The oogenesis could be subdivided into four stages: (1) Oogonia with a dark nucleus and a dark, ribosome-rich cytoplasm. (2) Early oocyte stage, represented by relatively small cells (10 μm in diameter), a cytoplasm showing some mitochondria and some endoplasmic reticula. (3) Previtellogenic stage, with a decrease of the nucleo-cytoplasmic ratio due to the remarkable increase in ooplasm volume. Immature eggshell globules are observed. (4) Vitellogenic stage, including early vitellogenic ovarian stage, in which a second type of globule (inclusion globule) is formed, and a late vitellogenic uterine stage, in which the inclusion globules are not present anymore. The mature eggshell globules form a peripheral layer under the cell membrane. Eggshell and inclusion globules were analyzed with electron energy loss spectroscopy, electron spectroscopic imaging, protease treatment, and with periodic acid thiocarbohydracide silver proteinate to detect polysaccharides. Chromatoid bodies are present in all four stages. For the first time in a flatworm, we provide evidence that accessory cells, forming a tunica around the ovarian follicles, are epithelial or epithelium-like and likely contribute nutrients for the growth of the oocytes.

Report this publication

Statistics

Seen <100 times