Effect of Sublethal Nickel Chloride Exposure on Crayfish, Astacus leptodactylus Ovary: An Ultrastructural, Autometallographic, and Electrophoretic Analyses

Cytological responses in different organs of sentinel organisms have proven to be useful tools for characterizing the health status of those organisms and assessing the impact of environmental contaminants. Our study shows that nickel (II) accumulated in both germ cells (oogonia and developing oocytes) and somatic cells (muscle cells, follicle cells) in the Astacus leptodactylus ovary. Muscle cells from ovarian wall show disorganization and the disruption of cytoplasmic microtubules and pyknosis of the cell nucleus. Follicle cells, both those that surround the developing oocytes and also those that are not associated with the oocytes contained within the cytoplasm vacuoles of different sizes, degenerated mitochondria, myelin bodies, disorganized microtubules, and pyknotic nuclei. The most evident pathological phenomenon was the alteration and disorganization of the basal matrix, which separates the ovarian interstitium from ovarian follicles compartment. Exposure to nickel induces cytoplasmic vacuolation in oogonia and developing oocytes, structural alteration of the developing yolk granules and condensation of the nucleoli. Ultrastructural autometallography has shown grains of silver-enhanced nickel inside the cytoplasm of the muscle cells with altered morphology, including the cytoplasm, nucleus, and basal matrix of the follicle cells, and in intracisternal granules and developing yolk granules of the oocytes.

Ultrastructural characteristics of the uterine epithelium of aspidogastrean and digenean trematodes

The ultrastructure of the uterus proper of the aspidogastrean Aspidogaster limacoides Diesing, 1835 and two digenean species, Phyllodistomum angulatum Linstow, 1907 (Plagiorchiida, Gorgoderidae) and Azygia lucii (Müller, 1776) (Strigeida, Azygiidae), was examined by transmission electron microscopy (TEM). The uterine epithelial lining of these species is thin, except for the perinuclear region of the epithelial cells. Septate junctions occur between adjacent epithelial cells within the uterine wall. The luminal surface of the cells is elevated into microlamellae, which project into the uterine lumen and cover the entire epithelial lining. Basally the uterine epithelium is attached to a basal matrix, and its supporting layers of muscle fibres are weak and composed of scattered circular muscles. Despite the marked similarity in the ultrastructural pattern of the aspidogastrean and two digeneans studied, there is some degree of variation in the secretory activity of their uterine epithelium. The high level of vesicular exocytotic activity in the epithelial cytoplasm of A. lucii may be associated with differences in egg emission and the subsequent life cycle involving a non-ciliated, non-swimming and non-free-living miracidium, as opposed to the free-swimming miracidium of P. angulatum. The similar nature of the uterine epithelium in all three species studied represents an ultrastructural marker possibly supporting a close phylogenetic relationship between the Aspidogastrea and the Digenea.

The ultrastructural localization of Echinococcus granulosus antigen 5

SUMMARYMurine monoclonal and polyclonal antisera, raised against the 38 kDa subunit of Echinococcus granulosus antigen 5, were used to investigate the tissue distribution of the antigen in hydatid cysts. Immunoreactivity was visualized by indirect immunofluorescence on whole protoscoleces, and ultrastructural immunocytochemistry utilizing colloidal gold-based labelling procedures on unsectioned and cryosectioned brood capsules and protoscoleces. In protoscoleces, the 38 kDa subunit of antigen 5 was localized at the interface of parenchymal cells and associated extracellular matrices, as well as along the interface of the tegumentary syncytium in the somal region and its basal matrix. Cytoplasmic labelling of parenchymal cells was rare; when observed, it was associated with vesicles and membranes in cytoplasmic extensions of parenchymal cells. In brood capsules, the antigen was associated with the external face of the plasma of degenerating parenchymal cells. The 38 kDa subunit occurs along the extracellular face of cell membranes, suggesting that antigen 5 is either a component of the membranes or associated extracellular matrices.