Search results for "Ultrastructure"
showing 10 items of 224 documents
Morphology of the male and female tergal glands of the woodroach Cryptocercus punctulatus (Insecta, Dictyoptera)
1989
Males and females of Cryptocercus punctulatus possess tergal glands which differ in position, size, morphology, and chemical composition of their secretions. Ultrastructural studies reveal the presence of class 1 and class 3 glandular units interspersed throughout the glands; class 3 glandular units are 30 times as numerous as in the female, but no cytological difference was found between the sexes. The morphology of the tergal glands is characterized by the occurrence of a subcuticular space reservoir, a dense tracheal system, and a thick collagenous layer instead of the typical basement membrane. Comparison with the termite abdominal gland system indicates a great similarity in the fine s…
The exocrine glands of Dysdercus cingulatus (Heteroptera, Pyrrhocoridae): Morphology and function of nymphal glands.
2018
The exocrine glandular system of the nymphs and the adults of Dysdercus cingulatus were studied. The D. cingulatus nymphs present 3 dorso-abdominal glands (lying under the 3rd, 4th, and 5th abdominal terga) and a pair of dorso-lateral pygidial glands on the pygidium (tergum 8). Histological and ultrastructural studies show that the upper and lower walls of the dorso-abdominal glands differ in structure; 3 types of cells were described: epidermal cells, unicellular secretory cells, and multicellular secretory units. Each of these exocrine glands plays an important part in the behavior of the nymphs (gregariousness, alarm, defense). The morphology of the various glands is discussed, and the c…
Immunodetection of the microvillous cytoskeleton molecules villin and ezrin in the parasitophorous vacuole wall of Cryptosporidium parvum (Protozoa: …
1999
Microvilli - actin - villin - ezrin - Cryptosporidium parvum The sporozoites and merozoites of the Apicomplexan protozoan Cryptosporidium parvum (C. parvum) invade the apical side of enterocytes and induce the formation of a parasitophorous vacuole which stays in the brush border area and disturbs the distribution of microvilli. The vacuole is separated from the apical cytoplasm of the cell by an electron-dense layer of undetermined composition. In order to characterize the enterocyte cytoskeleton changes that occur during C. parvum invasion and development, we used both confocal immunofluorescence and immunoelectron microscopy to examine at the C.parvum-enterocyte interface the distributio…
Prenatal Ultrastructural Diagnosis in the Neuronal ceroid-lipofuscinoses
1994
Summary The neuronal ceroid-lipofuscinose (NCL) are autosomal-recessive disorders in childhood of unknown enzymatic origin. They can be recognized by the presence of abnormal lipopigments identified by electron microscopy. Based on the study of circulating lymphocytes, individual clinical subtypes of NCL can be correlated. Prenatal diagnosis of NCL with the electron microscope is now feasible for the infantile (Finnish) from (INCL) and late-infantile form (LINCL). INCL-specific granular lipopigments are present in endothelial cells of biopsied chorion stroma vessels of homozygously affected fetuses. In LINCL, disease-typical curvilinear bodies can be identified in uncultured amniotic fluid …
Ultrastructural myopathology in the molecular era.
2013
Electron microscopy is an essential component of myopathology, both in diagnostics and research of neuromuscular diseases. Although recently reduced in the diagnostic armamentarium, it has greatly been expanded to mouse models in research. Mostly it is descriptive, but a few additional techniques in combination with transmission electron microscopy have been employed. Foremost among them is immunoelectron microscopy, which assists in guiding molecular analysis in hereditary conditions, but may be vital in diagnostics of certain acquired entities, e.g., undulating tubules in dermatomyositis and in those congenital myopathies where genes and mutations remain to be identified, as in cylindrica…
Pachyjoenia howa, a new symbiotic parabasalid joeniid flagellate of the termite Postelectrotermes howa
2005
The Joenia-like lophomonad of Postelectrotermes howa is identified by light and electron microscopy as a new genus and species Pachyjoenia howa. Its flagellar area of about 1800 flagella is dome shaped. Basal bodies bear a composite root oriented counterclockwise in addition to the clockwise hook-shaped lamina present in other joeniids. There are four parallel privileged basal bodies. The main parabasal fibre is twisted around the axostyle and splits into several branches bearing Golgi bodies. The axostyle trunk is conspicuous and composed of a bundle of ∼90 small axostyles. There are sausage-shaped bacterial endosymbionts mixed with hydrogenosomes in the cytoplasm and coccoid bacterial end…
Histological and electron microscopical observations on the effects of lead on gills and midgut gland ofProcambarus clarkii
1991
Adult intermolt specimen of Procambarus clarkii (Crustacea, Decapoda) have been treated for 96 hours in aquaria with 100mg/l of lead. The gills and midgut gland were processed and studied in the electron microscope. The gill filament shows important changes in the ultrastructure of the epithelial cells and the cuticle. The hepatopancreatic cells studied (i.e. the vacuolated and dark cells) do not show noticeable structural changes but accumulate lead (electrondense precipitates) mainly in lysosomes.
Amylopectin: a major component of the residual body inCryptosporidium parvumoocysts
2004
Amylopectin is used for carbohydrate storage in different life-stages of a number of apicomplexan parasites. We have performed an ultrastructural analysis of amylopectin granules from the oocyst residual body and sporozoites ofCryptosporidium parvum. Amylopectin granules were studiedin situand after isolation from ‘French’ press disrupted parasites, by conventional transmission electron microscopy (TEM) of sectioned oocysts and various negative staining and cryoelectron microscopy techniques. Within the membrane-enclosed oocyst residuum large amylopectin granules (0·1–0·3 μm) can be found besides a characteristic large lipid body and a crystalline protein inclusion. Smaller granules were de…
MITOCHONDRIOGENESIS IN MATURING SEA URCHIN OOCYTES: A COMPUTERIZED RECONSTRUCTION ANALYSIS
1996
Abstract The dynamics of chondriome changes in oogenesis of the sea urchinParacentrotus lividuswere studied by electron microscopy. An oocyte-enriched fraction obtained by gonad mechanical dissociation without protease treatment was used. The shape, size and arrangement of mitochondria (Mt) in cells were quantitatively analysed on the basis of data from reconstruction experiments, with serial sections performed using a specific computer program. At all stages of oogenesis, the chondriome was shown to consist of rod-shaped Mt of various lengths and also of small amounts of globular Mt about 0.3 μm in diameter. Chondriome transformation during oogenesis is shown to involve the following proce…
Development of the filiform hairs on the cerci of Gryllus bimaculatus Deg. (Saltatoria, Gryllidae)
1978
The filiform hairs, mechanoreceptors of Gryllus, pass through six developmental stages during the last larval stage. The cytoplasm of their sense cells suggests intensive synthesis of protein for cellular metabolism and intercytoplasmic exchange of material via glial evaginations. Ultrahistochemical tests demonstrated acid phosphatase in the lysosomes as well as in components of the Golgi apparatus. There was no significant change in the appearance of the sense cell cytoplasm, indicating a maintained functional state also during molting. The new cuticular apparatus is formed after apolysis by the three enveloping cells. Formation of the replacement hairs is initiated by a cytoplasmic outgro…