Search results for "Ultrastructure"
showing 10 items of 224 documents
Ultrastructure of Joenoides intermedia (Grassé 1952), a symbiotic parabasalid flagellate of Hodotermes mossambicus, and its comparison with other joe…
2003
Light and electron microscopy confirms the validity of the genus Joenoides. The cell is organised like other joeniids with a triangular flagellar area of about two thousand flagella/basal bodies and three privileged basal bodies located apart at the anterior corner of the flagellar area. Characteristically, the two parabasal fibres attached to the basal body #2 are very large and composed of striated subfibres that spread in the cytoplasm, where they sustain Golgi bodies. The flagellar area is surrounded by the axostylar capitulum, which is underlain by a thick layer of preaxostylar fibres, a very strongly amplified component in this species. The axostylar trunk is composed of a bundle of m…
The floral nectaries in theLimnanthaceae
1992
Floral nectaries in theLimnanthaceae are established as exoscopic basal bulges of the episepalous stamens. Their nectariferous tissues include the epidermis and hypodermal parenchyma and inLimnanthes are vascularized by phloematic branches of the staminal bundles. Secretion occurs mainly through anomocytic stomata but, in addition, probably through the outer cuticularized thin walls of the epidermal cells. The flower structure is comparatively simple. The nectar is often slightly concealed. A wide range of pollinators can be expected, but bees are observed to be the dominant ones. The systematic position of the family is still obscure. Taxonomic placement near to any other geranialian famil…
Immunological and ultrastructural characterization of spirotrichonymphid flagellates from Reticulitermes grassei and R. flavipes (syn. R. santonensis…
2006
AbstractFive species of spirotrichonymphids representing three genera have been studied by light and immunofluorescence microscopy, and by transmission electron microscopy. The genus Spirotrichonympha, represented by S. flagellata from Reticulitermes grassei, is characterized by a compound axostyle composed of several fibers or subaxostyles. The genus Spironympha, represented by S. kofoidi from Reticulitermes flavipes (syn. R. santonensis) and by the two new species S. verticis and S. lanceata, is characterized by flagellar lines restricted to the anterior area and a simple, tubular axostyle. Spironympha verticis and S. lanceata are mainly distinguished by ultrastructural details of their f…
TEM observations on symbionts ofJoenia annectens(Flagellata Hypermastigida)
2001
Transmission electron microscopy was used to evaluate the ultrastructural morphology of some other symbiotic prokaryotes of Joenia annectens, an intestinal flagellate of the termite Kalotermes flavicollis. Three morphotypes are predominant and recognizable from their morphological characteristics. One morphotype is represented by spirochaetes that are mainly external and cover the flagellate, helping its movement. Rod-shaped bacteria, which represent the second morphotype, are also attached to the surface among the spirochaetes. Rod-shaped bacteria and some spirochaetes may enter the cell surface of Joenia annectens as a consequence of phagocytosis, remaining enclosed in an envelope of plas…
The flagellates of the termite Hodotermopsis sjoestedti with special reference to Hoplonympha, Holomastigotes and Trichomonoides trypanoides n. comb.
2004
Abstract The termite Hodotermopsis sjoestedti harbours a symbiotic fauna of protists comprising at least 11 genera and a much larger number of species. Two oxymonad genera, Pyrsonympha and Dinenympha, are mixed with nine parabasalid genera, two trichomonads, Trichomitopsis termopsidis and Trichomonoides trypanoides n. comb., four spirotrichonymphid genera/species: Spirotrichonympha, Microjoenia, Holomastigotes lanceolata n. sp., Holomastigotes elongatum and three trichonymphid genera/species; Hoplonympha natator, Eucomonympha, Trichonympha. Hoplonympha natator has two anterior symmetrical bundles of ∼60 basal bodies/flagella separated by two parabasal plates. The cell surface is crenelated …
Ultrastructure and freeze-fracture studies of the thylakoids ofMantoniella squamata (Prasinophyceae)
1988
The ultrastructure and the supramolecular organization of the thylakoids of the small green flagellate,Mantoniella squamata, were examined in thin sections and freeze-fracture preparations. The whole chloroplast is tightly packed with thylakoids, which show a pattern of meandering, branching and/or anastomosing membranes. In freeze-fracture preparations only two fracture-faces can be distinguished: the PF- and the EF-face. The PF-face has a much higher particle density than the EF-face (PF: 4086 particles/μm2; EF: 865 particles/μm2). The EF-face is not as uniform as the PF-face. The areas which are packed with particles probably correspond to closely appressed thylakoid regions or adhesive …
The compound internal pyrenoid in cultured cells of the green algaMonoraphidium griffithii (Berkel.) Komar.-Legner.
1979
The chloroplast ultrastructure ofMonoraphidium griffithii (Berkel.) Komar.-Legner. has been studied in axenic cultures of various ages. The algae have grown in a complete nutrient solution (illumination about 3,000 lx) and on its agar medium (illumination about 600 lx). The large parietal cup-shaped chloroplast of the cells includes a multiformed compound internal pyrenoid that is situated, especially in older cells, in the central part of the chloroplast opposite to the dictyosome and the nucleus. The chloroplast thylakoids either reach the edge of the pyrenoid or penetrate its matrix and run there parallel in more or less long bits. Starch grains were not found to form any sheath around t…
Investigations on the Starch Content and Ultrastructure of Spruce Needles Relative to the Occurrence of Novel Forest Decline
1989
The starch content and ultrastructure of needles of Norway spruce trees [Picea abies (L.) Karst.] taken from three natural habitats, undamaged or with symptoms of novel forest decline, were investigated during the course of three years. The starch content was clearly dependent on the seasons, with a maximum in spring and a decline during summer and autumn, leading to a minimum in winter. Needles of damaged trees from one habitat exhibited in all three years from August to October a significantly higher starch content than their undamaged counterparts. Microscopic investigations of these needle samples exhibited severe damage symptoms to the phloem in macroscopically green needles, though mo…
Cryptosporidium parvum: Structural Components of the Oocyst Wall
1999
Cryptosporidium parvum, an enteropathogenic parasite, infects a wide range of mammals including man and constitutes a substantial veterinary and medical threat due to its ubiquitous distribution and the stability of the oocyst stage. The oocyst wall of C. parvum is known to be extremely resistant to chemical and mechanical disruption. Isolated oocyst walls are shown by both thin sectioning and negative staining transmission electron microscopy to possess a filamentous array on the inner surface. This filamentous array can be greatly depleted by digestion with proteinase K and trypsin, but pepsin has less effect. Ultrasonication of the untreated oocyst walls produced almost no fragmentation,…
Contribution of microscopy to the study of proliferating blood cells in Ciona intestinalis immune response
2010
Following an inflammatory stimulus such as the injection of erythrocytes into the tunic of Ciona intestinalis, hemocytes respond to events occurring in the tunic within a short time, and infiltrate the inflamed tissue being massively involved in the acute inflammatory response and capsule formation. The proliferative response of circulating hemocytes and pharynx assume particular interest as it is significantly enhanced during these defence reactions. Microscopy clearly may contribute to extend our understanding of the phenomenon showing interesting mitotic figures and hematogenic nodules with proliferative characteristics.