Electron-dense Bodies (electron-dense + body)

Distribution by Scientific Domains


Selected Abstracts


Ultrastructure and functional features of midgut of an adult water mite Teutonia cometes (Koch, 1837) (Hydrachnidia: Teutoniidae)

ACTA ZOOLOGICA, Issue 2 2010
Andrew B. Shatrov
Abstract Shatrov, A. B. 2010. Ultrastructure and functional features of midgut of an adult water mite Teutonia cometes (Koch 1837) (Hydrachnidia: Teutoniidae). ,Acta Zoologica (Stockholm) 91: 222,232 The midgut of the adult water mite Teutonia cometes (Koch 1837) (Hydrachnidia: Teutoniidae) was investigated by means of transmission electron microscopy and on semi-thin sections. The midgut is represented by a blind sac composed of the narrow ventriculus, two proventricular lateral diverticula and three pairs of postventricular caeca. A single-layered epithelium consists of one type of endodermal digestive cells of quite different shape and size, which may form protrusions into the midgut lumen. The large nuclei are frequently lobed and contain one to three nucleoli. The apical cell membrane forms short scarce microvilli, between their bases the pinocytotic vesicles of unspecific macropinocytosis as well as the narrow pinocytotic canals are formed and immersed into the cell. The intracellular digestion of the food ingested into the midgut after extraintestinal digestion is predominant. The pinocytotic vesicles fuse with small clear vesicles of proposed Golgi origin to form secondary lysosomes. The digestive cells also contain small amounts of rough endoplasmic reticulum, variously structured heterolysosomes, residual materials in the form of both the small electron-dense bodies and the large variously granulated substances, reserve nutritive materials such as lipid and glycogen, as well as clear vacuoles. Residual materials are obviously extruded from the cells into the gut lumen. [source]


Secretory products of the haptoral reservoirs and peduncular glands in two species of Bravohollisia (Monogenea: Ancyrocephalidae)

INVERTEBRATE BIOLOGY, Issue 2 2008
Wey-Lim Wong
Abstract. Light and electron microscopy were used to characterize the structure of secretory cells and their products involved in attachment of two monogenean parasites of fish, in order to understand their role in the attachment process. In Bravohollisia rosetta and Bravohollisia gussevi, peduncular gland cells with two nuclei, granular endoplasmic reticulum, and Golgi bodies produce dual electron-dense (DED) secretory bodies with a homogenous electron-dense rind and a less electron-dense fibrillar core (oval and concave in B. rosetta and oval in B. gussevi). The DED secretory bodies are altered as they migrate from the gland cell to the haptoral reservoir, the superficial anchor grooves, and into the gill tissues. The contents of the DED secretory bodies are exocytosed into the reservoirs, fibrillar cores persisting in the matrix, some of which condense, forming highly electron-dense spherical bodies. Small, oval, electron-dense bodies occur in the grooves, while no inclusions are visible in the homogenous exudate within the gill tissues. The single tubular extension of the reservoir enters a bifurcate channel within the anchor via a concealed, crevice-like opening on one side of the anchor. The channel directs secretions into the left and the right grooves via concealed apertures. The secretions, introduced into the tissues by the anchors, probably assist in attachment. The secretions are manifested externally as net-like structures and observed in some cases to be still attached to the point of exudation, on anchors detached from the gill tissues. This suggests that despite having the anchors detached, the worms can still remain anchored to the gill tissues via these net-like structures. Based on this, it is postulated that the net-like secretions probably function as a safety line to anchor the worm during the onset of locomotion and in doing so reduce the risk of tearing host tissues. [source]


Angiokeratoma corporis diffusum (Anderson,Fabry's disease): a case report

JOURNAL OF THE EUROPEAN ACADEMY OF DERMATOLOGY & VENEREOLOGY, Issue 2 2000
Daniela Massi
Abstract We report on a 14-year-old boy who presented with a 4-year history of acral pains and febrile episodes. On physical examination, numerous small reddish papules were present on his abdomen, located predominantly on the periumbelical region. Renal function was within normal limits. Ophthalmological examination revealed whorled opacities of the cornea (cornea verticillata) and dilated tortuous conjunctival vessels. Histopathological examination of one of the cutaneous papules showed several dilated blood vessels in the superficial dermis surrounded by collarettes of thickened rete ridges, consistent with a diagnosis of angiokeratoma. The electron-microscopic study of a skin specimen demonstrated the presence of dilated lysosomes with deposition of electron-dense bodies, some of which with laminated structure, in endothelial cells and fibroblasts. These findings were regarded as indicative of Fabry's disease. Subsequent biochemical analysis confirmed the presence of a ,-galactosidase A deficiency in leukocytes. In conclusion, we described the clinical, histopathological and submicroscopic findings of a case of Fabry's disease, in which the combination of electron microscopic and biochemical approaches allowed the correct diagnosis. [source]


Sperm morphology in the black coral Cirrhipathes sp. (Anthozoa, Antipatharia)

INVERTEBRATE BIOLOGY, Issue 3 2008
Elda Gaino
Abstract. Male polyps of the antipatharian Cirrhipathes sp., collected along the coral reef of Siladen Island (Sulawesi, Indonesia), were studied in order to gain an insight into the reproductive biology. Spermatocysts (maximum size 120 ,m) are located within the primary gametogenic mesenteries and are separated by mesenteric cell cytoplasmic extensions. Sperm, maturing along radial rows, have a fairly round shape and contain a series of electron-dense vesicles in the apical nuclear region. A single mitochondrion flanks the nucleus. A peculiar cup-like electron-dense body, edged with regularly spaced electron-dense granules, is interposed between the nucleus and the tail, and delimits a central region that includes two centrioles. Cross-sections of the cup-like body reveal that the distal centriole has a pericentriolar system, consisting of nine arms arranged in a radial pattern. Each arm branches into three processes that are connected to the electron-dense granules. Indirect evidence of spawning is derived from the accumulation of sperm in the gastric cavity. This process takes place through the lysis of the cells bordering the mesenteries. Intact cells of this bordering layer appear to be involved in the phagocytosis of non-expelled gametes. [source]