Formation of the Paruterine Capsules and Embryonic Envelopes in Cylindrotaenia-Hickmani (Jones, 1985) (Cestoda, Nematotaeniidae)

1988 ◽  
Vol 36 (5) ◽  
pp. 545 ◽  
Author(s):  
MK Jones
Keyword(s):  
Electron Microscopy ◽  
Life Cycles ◽  
Outer Envelope ◽  
Capsule Formation ◽  
Cellular Processes ◽  
Sequence Of Events ◽  
Transmission Electron ◽  
Early Embryos ◽  
Outer Capsule ◽  
Inner Envelope

The development of embryonic envelopes and paruterine capsules in Cylindrotaenia hickmani (Jones 1985) Jones, 1987 were studied using transmission electron microscopy. The embryonic envelopes of C. hickmani form in a similar way to those of other cyclophyllideans. The extant embryonic envelopes in fully developed eggs are: the thin, featureless outer envelope; the inner envelope, which forms an oncospheral membrane; embryophore; and an electron-dense peripheral cytoplasmic layer that lies immediately internal to the external plasma membrane of the inner envelope. Processes of uterine epithelial cells envelop the outer capsule of early embryos. Both the uterine envelope and outer capsule are lost as eggs develop. Paruterine organs are complex, paired structures that form lipid and flattened cellular processes for inclusion within paruterine capsules. Paruterine capsules are complex parenchymal structures containing eggs and the products of the paruterine organs. The possession of such complex paruterine envelopes suggests that the life cycles of nematotaeniids are terrestrial. The sequence of events in paruterine capsule formation in nematotaeniids is unlike that seen in other cyclophyllidean groups with paruterine capsules and it is unlikely that nematotaeniids are closely related to such cestodes.

Dipetalonema viteae: ultrastructural study on the in vitro interaction between rat macrophages and microfilariae in the presence of IgE antibody

Parasitology ◽  
1981 ◽  
Vol 82 (1) ◽  
pp. 55-62 ◽  
Author(s):  
M. A. Ouaissi ◽  
A. Haque ◽  
A. Capron
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Ultrastructural Study ◽  
Peritoneal Macrophages ◽  
Immune Serum ◽  
Sequence Of Events ◽  
Transmission Electron ◽  
Dipetalonema Viteae ◽  
In Vitro Interaction

SUMMARYThe in vitro interaction between rat peritoneal macrophages and Dipetalonema viteae microfilariae in the presence of amicrofilaraemic rat immune serum was studied by transmission electron microscopy. The probable sequence of events leading to the killing of D. viteae microfilaria by macrophages is as follows. (a) Rat peritoneal macrophages in the presence of amicrofilaraemic rat immune serum adhere to the parasite surface, (b) the macrophages extend their pseudopodia around the parasite, (c) the ‘lysosome-like’ granules discharge their contents on to the parasite surface, (d) the lytic activity of these products begins at the parasite surface and (e) subsequent breaking of the microfilarial cuticle occurs, exposing the parasite intracellular material.

Egg ultrastructure of the amabiliid cestode Tatria biremis Kowalewski, 1904 (Cyclophyllidea, Amabiliidae), with an emphasis on the oncospheral envelopes

2013 ◽  
Vol 58 (3) ◽  
Author(s):  
Vasyl Tkach ◽  
Zdzisław Świderski ◽  
Daniel Młocicki
Keyword(s):  
Cell Types ◽  
Life Cycles ◽  
Intermediate Hosts ◽  
Outer Envelope ◽  
Ultrastructural Studies ◽  
Egg Maturation ◽  
Ultrastructural Characteristics ◽  
Egg Envelopes ◽  
Host Infection ◽  
Inner Envelope

AbstractThis is the first report on the ultrastructure of eggs in the cestode family Amabiliidae Braun, 1900. The gravid proglottides of Tatria biremis easily detach from the strobila. Their thick-walled saccate uterus contains numerous rounded or oval eggs measuring about 30-32 μm in diameter. In the early preoncospheral phase, three primary embryonic envelopes are formed around the developing and differentiating embryos, namely: (1) vitelline capsule originating from vitellocyte material; (2) outer envelope formed by two macromeres, and (3) inner envelope originating from a fusion of three mesomeres. Thus, both the outer and inner envelopes of T. biremis eggs are cellular in origin and syncytial in nature. During egg maturation, the three primary embryonic envelopes undergo differentiation into fully formed oncospheral or egg envelopes. Most significant changes were observed in the inner envelope which becomes progressively subdivided into 3 sub-layers: the extra-embryophoral sub-layer, the embryophore, and the intra-embryophoral sub-layer, containing mesomere nuclei. The mature hexacanth is covered by a thin layer of the oncospheral tegument. Within the infective hexacanth larva, five cell types were distinguished: (1) a binucleated subtegumental cell; (2) U-shaped penetration gland; (3) nerve cells; (4) somatic cells representing the myocytons of both somatic and hook musculature, and (5) large germinative cells. Ultrastructural characteristics of T. biremis eggs are compared with those described in representatives of other cestode taxa. Since the functional ultrastructure of cestode egg envelopes is defined by multiple factors such as the type of life cycles, habitats and behaviour of the intermediate hosts, mode of the intermediate host infection, etc., ultrastructural studies of the greater diversity of cestodes are needed to obtain comparative data for fruitful analysis of cyclophyllidean cestode adaptations to their diverse life cycles.

Papilla response of barley epidermal cells caused by Erysiphe graminis: rate and method of deposition determined by microcinematography and transmission electron microscopy

1979 ◽  
Vol 57 (8) ◽  
pp. 898-913 ◽  
Author(s):  
Richard J. Zeyen ◽  
W. R. Bushnel
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Amorphous Material ◽  
Time Lapse ◽  
Epidermal Cells ◽  
Erysiphe Graminis ◽  
Sequence Of Events ◽  
Transmission Electron ◽  
Wall Appositions ◽  
Entire Sequence

Papillae were deposited in barley epidermal cells directly beneath appressoria of Erysiphe graminis f. sp. hordei and appeared as hemispherical, internal wall appositions. The papilla response began shortly after the formation of a rapidly moving cytoplasmic aggregate beneath the appressorium. As documented in coleoptile tissue by time-lapse light microcinematography, the papillae grew rapidly for 20–30 min after becoming visible, their radii increasing by 0.1 μm/min. For small papillae, deposition continued for about 30 min; for larger papillae, deposition continued for 120–180 min. Results with transmission electron microscopy on leaf epidermal cells suggested that papilla deposition by host cytoplasmic aggregates can be divided into four sequential stages: (i) the deposition of osmiophilic (lipidic) materials, (ii) the deposition and partial compaction of nonosmiophilic, amorphous material (probably insoluble polysaccharides), (iii) compaction of nonosmiophilic, amorphous material, and (iv) the incorporation of osmiophilic material into the host wall and into the compacted nonosmiophilic, amorphous material. At maturity, the papillae are hardened, electron-opaque wall appositions that may be effective in preventing fungal penetration and development. Failure of papillae to prevent fungal penetration and development may be related to the inability of the epidermal cells to complete the entire sequence of events in papilla deposition before attempted fungal penetration.

A temperature-jump technique for time-resolved cryo-transmission Electron Microscopy

1989 ◽  
Vol 47 ◽  
pp. 742-743
Author(s):  
H. Chestnut ◽  
D. P. Siegel ◽  
J. L. Burns ◽  
Y. Talmon
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Liquid Crystalline ◽  
Temperature Jump ◽  
Specimen Preparation ◽  
Thin Specimen ◽  
Time Resolved ◽  
Sequence Of Events ◽  
Transmission Electron ◽  
Focused Beam

Transmission electron microscopy of rapidly-frozen, hydrated specimens (cryo-TEM) is a powerful way of examining labile microstructures. This technique avoids some artifacts associated with conventional preparative methods. Use of a controlled environment vitrification system (CEVS) for specimen preparation reduces the risk of unwanted sample changes due to evaporation, and permits the examination of specimens vitrified from a defined temperature. Studies of dynamic processes with time resolution on the order of seconds, in which the process was initiated by changes in sample pH, have been conducted. We now report the development of an optical method for increasing specimen temperature immediately before vitrification. Using our method, processes that are regulated by temperature can be initiated in less than 500 msec on the specimen grid. The ensuing events can then be captured by plunge-freezing within an additional 200 msec.Dimyristoylphosphatidylcholine (DMPC) liposomes, produced by extrusion, were used as test specimens. DMPC undergoes a gel/liquid crystalline transition at 24°C, inducing a change in liposome morphology from polyhedral to spherical. Five-μl aliquots of DMPC dispersions were placed on holey-carbon-filmed copper grids mounted in the CEVS environmental chamber, and maintained at 6-8°C and 80% relative humidity. Immediately before the temperature jump most of the sample was blotted away with filter paper, leaving a thin specimen film on the grid. Upon pressing the trigger, an electronic control circuit generated this timed sequence of events. First, a solenoid-activated shutter was opened to heat the specimen by exposing it for a variable time to the focused beam of a 75W Xenon arc lamp. Simultaneously, a solenoid-activated cryogen shutter in the bottom of the CEVS was opened. Next, the lamp shutter was closed after the desired heating interval. Finally, a solenoid-activated cable release was used to trigger a spring-loaded plunger in the CEVS, propelling the sample into a reservoir of liquid ethane. Vitrified samples were subsequently transferred to a Zeiss EM902 TEM, operated in zero-loss brightfield mode, for examination at −163°C.

scholarly journals Bacteriophages fEV-1 and fD1 Infect Yersinia pestis

Viruses ◽  
2021 ◽  
Vol 13 (7) ◽  
pp. 1384
Author(s):  
Mikael Skurnik ◽  
Salla Jaakkola ◽  
Laura Mattinen ◽  
Lotta von Ossowski ◽  
Ayesha Nawaz ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Escherichia Coli ◽  
Yersinia Pestis ◽  
Yersinia Pseudotuberculosis ◽  
Genomic Analysis ◽  
Sewage Water ◽  
Life Cycles ◽  
Genome Sequences ◽  
Transmission Electron ◽  
The One

Bacteriophages vB_YpeM_fEV-1 (fEV-1) and vB_YpeM_fD1 (fD1) were isolated from incoming sewage water samples in Turku, Finland, using Yersinia pestis strains EV76 and KIM D27 as enrichment hosts, respectively. Genomic analysis and transmission electron microscopy established that fEV-1 is a novel type of dwarf myovirus, while fD1 is a T4-like myovirus. The genome sizes are 38 and 167 kb, respectively. To date, the morphology and genome sequences of some dwarf myoviruses have been described; however, a proteome characterization such as the one presented here, has currently been lacking for this group of viruses. Notably, fEV-1 is the first dwarf myovirus described for Y. pestis. The host range of fEV-1 was restricted strictly to Y. pestis strains, while that of fD1 also included other members of Enterobacterales such as Escherichia coli and Yersinia pseudotuberculosis. In this study, we present the life cycles, genomes, and proteomes of two Yersinia myoviruses, fEV-1 and fD1.

Ciliary band formation in the doliolaria larva of Florometra

Development ◽  
1986 ◽  
Vol 96 (1) ◽  
pp. 303-323
Author(s):  
T. C. Lacalli ◽  
J. E. West
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Band Pattern ◽  
Ciliated Epithelium ◽  
Ciliary Band ◽  
Band Formation ◽  
Sequence Of Events ◽  
Transmission Electron ◽  
Direct Formation ◽  
Initial Pattern

The development of ciliary band pattern in the doliolaria larva of Florometra serratissima is described based on scanning and transmission electron microscopy. The uniformly ciliated epithelium of the post-hatching larva develops four regularly spaced bands over a period of approx. 20 h generating an epithelial pattern that is, essentially, a series of stripes. The first visible events of pattern formation progress over the larval surface in a posterior-to-anterior and dorsal-to-ventral sequence, but the initial pattern is not, in fact, striped. It instead consists of a close-packed array of oval interband domains separated and surrounded by belts of band cells. Secondarily the interband domains expand laterally and coalesce to form continuous, broad stripes, while the bands remain as narrow stripes between them. Two possible explanations for this unusual sequence of events are discussed: (1) that it can be understood in evolutionary terms with reference to band pattern in other echinoderm larvae, and (2) that it is a morphogenetic necessity because limitations inherent in the patterning mechanism prevent the direct formation of regular stripes.

Ultrastructural studies on egg envelopes surrounding the miracidia of Mediogonimus jourdanei Mas-Coma et Rocamora, 1978 (Digenea, Microphalloidea, Prosthogonimidae)

2010 ◽  
Vol 55 (3) ◽  
Author(s):  
Zdzisław Świderski ◽  
Abdoulaye Bakhoum ◽  
Daniel Młocicki ◽  
Jordi Miquel
Keyword(s):  
Electron Microscopy ◽  
Lipid Droplets ◽  
Freeze Substitution ◽  
High Pressure Freezing ◽  
Ultrastructural Studies ◽  
Transmission Electron ◽  
Egg Envelopes ◽  
Egg Shell ◽  
Means Of Transmission ◽  
Inner Envelope

AbstractThe intrauterine, mature and fully embryonated eggs of the prosthogonimid trematode Mediogonimus jourdanei Mas-Coma et Rocamora, 1978 were examined by means of transmission electron microscopy (TEM), using high pressure freezing, freeze substitution and infiltration with resin techniques. Each embryonated egg is composed of a miracidium surrounded by three envelopes: (1) the egg shell, (2) the outer and (3) inner envelopes. Egg envelopes play an important role in the protection, metabolism, storage of nutritive reserves and the general biology of the M. jourdanei egg. The inner envelope is characterised by large, flattened nuclei, and its syncytial cytoplasm contains a heavy accumulation of glycogen, lipid droplets, mitochondria and large vesicles. These traits indicate that this layer has the features of a metabolically-active syncytial layer with an energy storage capability. In the infective eggs observed before the hatching of the miracidium, areas of so-called “focal cytoplasmic degradation” were frequently observed, which may be involved in the autolytic process of all components of this envelopes.

Hymenolepis diminuta: the mechanism of egg hatching

Parasitology ◽  
1982 ◽  
Vol 85 (2) ◽  
pp. 237-250 ◽  
Author(s):  
S. D. Holmes ◽  
I. Fairweather
Keyword(s):  
Electron Microscopy ◽  
Hymenolepis Diminuta ◽  
Energy Reserves ◽  
Egg Hatching ◽  
Gelatinous Layer ◽  
Transmission Electron ◽  
Stage 4 ◽  
Stage 1 ◽  
Inner Envelope

SUMMARYThe fine structure and histochemistry of the envelopes surrounding the mature oncosphere of Hymenolepis diminuta have been investigated by transmission electron microscopy and light microscope observations of JB-4 embedded material. The fate of these envelopes during the hatching sequence in vitro has been followed by phase-contrast and scanning electron microscopy. Hatching is considered to comprise 4 stages. Stage 1 involves the mechanical breakage and removal of the shell and the outer cytoplasmic layer of the inner envelope; Stage 2 the activation of the oncosphere and the swelling of the gelatinous layer of the inner envelope; and Stage 3 the digestion and rupture of the embryophore. This is accomplished both by secretions from the penetration gland and by the action of external digestive enzymes, together with hook activity. Trypsin is more effective than amylase in digesting the embryophore. Stage 4 involves the enzymatic weakening of the gelatinous layer which helps the oncosphere to tear itself free with its hooks. Amylase is more effective than trypsin in attacking the gelatinous layer. On emergence from the gelatinous layer, the oncosphere is still enveloped by the ‘oncospheral membrane’, although this covering is soon lost. Once activated, the oncosphere is capable of completing the hatching sequence by itself, without the addition of enzymes. This process is a lengthy one, however, taking up to 2 h, and the expenditure of its glandular and energy reserves makes successful gut penetration by the oncosphere unlikely.

Electron microscopy of embryonic envelope formation by the cestode proteocephalus longicollis (zeder, 1800)(proteocephalidea)

1978 ◽  
Vol 36 (2) ◽  
pp. 444-445
Author(s):  
Z. Swiderski ◽  
L. Subilia
Keyword(s):  
Electron Microscopy ◽  
Outer Envelope ◽  
Vitelline Cell ◽  
Fibrillar Material ◽  
Initial Stage ◽  
Advanced Stages ◽  
Vitelline Cells ◽  
Shell Globule ◽  
Pass Through ◽  
Inner Envelope

Four main embryonic envelopes, the capsule, outer envelope, inner envelope and oncospheral membrane, are formed around the developing embryos of Proteocephalus longicollis, a parasite of fishes.The capsule, formed from shell-globule material of vitelline cells, is the first embryonic envelope which encloses the fertilized oocyte and a single vitelline cell (Fig. 1) when they pass through the ootype and enter the uterus. At this initial stage of embryogenesis, the capsule is formed of two closely apposed membranes (Fig. 1, inset). In more advanced stages, the capsule slightly increases its volume, and a fine-fibrillar material accumulates in the space between its two limiting membranes (Fig. 2).

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