Search results for "Electron microscope"
showing 10 items of 784 documents
Spectral and microscopic study of self-assembly of novel cationic spermine amides of betulinic acid
2016
Supramolecular characteristics of two spermine amides of betulinic acid (1 and 2) were studied by measuring and evaluating their UV-VIS-NIR spectra in aqueous acetonitrile and DOSY-NMR spectra in tetradeuteromethanol, accompanied by atomic force microscopy (AFM) images, scanning electron microscopy (SEM) micrographs, and transmission electron microscopy (TEM) micrographs. Fibrous supramolecular self-assembly of 1 and 2 was observed by AFM images, as well as by the SEM and TEM micrographs. Bathochromic shifts of the absorbance maximum at 870nm to 1015-970nm in the UV-VIS-NIR spectra were observed with increasing water content in the acetonitrile/water systems, indicating formation of fibrous…
Senile amyloidosis: Principles of localization in a heterogeneous form of amyloidosis
1983
In order to identify amyloid deposits in patients over 60 years of age (so-called senile amyloid), the following five tissues were investigated under the light and electron microscope : 1. pituitary gland, 2. pancreatic islets of Langerhans, 3. heart, 4. aorta, and 5. brain. In all an increasing incidence of amyloid deposits was found with increasing age, and in the brain a significant quantitative increase in amyloid deposits with increasing age was observed. Despite the biochemical heterogeneity of amyloid found in old age, all the deposits seen in tissues examined were morphologically similar. Typical amyloid fibrils were always found (diameter 60–100 A), and these were invariably deposi…
Metachromatic staining and electron dense reaction of glycosaminoglycans by means of Cuprolinic Blue
1987
The cationic phthalocyanin-like dye Cuprolinic Blue, unlike phthalocyanin dyes such as Alcian Blue or Astra Blue, can definitely exhibit a clear metachromatic reaction with appropriate substrates. The application of Cuprolinic Blue to epoxy-embedded semithin sections revealed that mast cell cytoplasmic granules, goblet cell mucin and cartilage matrix stained in violet shades (metachromatic), whereas nuclear chromatin presented a bright blue coloration (orthochromatic). The metachromatic structures showed a high degree of contrast when ultrathin sections treated with Cuprolinic Blue were examined by electron microscopy. Cytophotometric measurements of stained components from the large intest…
Inverse behaviour of "synaptic" ribbon and spherule numbers in the pineal gland of male guinea-pigs exposed to continuous illumination.
1986
There is increasing evidence that pineal “synaptic” ribbons are a heterogeneous population of organelles. In addition to “synaptic” ribbons (SR) sensu stricto, which consist of an electron-dense rod surrounded by electronlucent vesicles, “synaptic” spherules (SS) exist, the electrondense core of which is round and much wider than that of the SR. In the guinea-pig SR and SS numbers exhibit an inverse day/night rhythmicity. To gain more insight into the functional significance of SR and SS, guinea-pigs were exposed to continuous illumination for approximately 4 months (LL) and the respective structures in the pineal gland were quantitated under the electron microscope and compared with contro…
Adaptation of the disector method to rare small organelles in TEM sections exemplified by counting synaptic bodies in the rat pineal gland
1997
The disector is the only objective method for quantifying particles of variable size in a given volume. With this method, cell organelles are identified on adjacent sections, but only those present in one section are counted. When counting extremely rare structures in transmission electron microscope sections (physical disector), the usual procedure of counting on electron micrographs is limited for economic reasons (e.g. micrographs highly outnumbering the investigated structures). Hence, to apply this unbiased stereological method, a modification of the physical disector concerning 3 aspects has been developed. (1) The prerequisite of screening large corresponding tissue areas (here appro…
Short-term response of three resin-based materials as desensitizing agents under oral environmental exposure
2012
Objective. This paper focuses on clinical responses after 7 days of oral exposure to two resin-based materials as desensitizing agents compared to a fluoride varnish and on morphological and analytical study as a means to elucidate the mechanism of action. Materials and methods. The elemental composition of Vertise™ Flow (VF), Universal Dentine Sealant (UDS) and Flor-Opal® Varnish (FOV) were investigated by using an X-ray energy dispersive spectrometer (EDX) in conjunction with a scanning electron microscope (SEM). SEM morphology of the material-treated dentine surfaces and pain reduction ability according to the Visual Analogue Scale (VAS) were evaluated in selected hypersensitive teeth. P…
Analysis of synaptic bodies in the Sprague–Dawley rat pineal gland under extreme photoperiods
2007
Synaptic bodies (SBs) are small, prominent organelles in pinealocytes, most probably involved in signal transduction processes. To check the influence of the photoperiod on their shape plasticity and number we chose two extreme lighting conditions, i.e. 20 h of illumination followed by 4 h of darkness (LD 20:4) versus (LD 4:20). Pineal glands were assessed at 0, 4 and 13 h after dark onset. Under both conditions reconstructed SBs were plates or ribbons but never spheres and there were no obvious differences in morphology. Photoperiodic changes in SB profile size and number were investigated: application of the established method for SB quantification based on single section profile counts (…
Strain differences in the ratio of synaptic body types in photoreceptors of the rat retina.
1993
In the retinal outer plexiform layer of seven different rat strains, synaptic bodies (SB) were counted and, according to their morphology, characterized as synaptic ribbons (SR), synaptic spheres (SS) or intermediate structures. It was found that absolute SB numbers showed relatively small variations while SR/SS ratios differed considerably between the strains investigated. These results are discussed with respect to retinal pigmentation and to formation and degradation, respectively, of synaptic ribbons.
Ultrastructural alterations and environmental exposure influence the opiate concentrations in hair of drug addicts
1995
Hair samples were taken at autopsy from the head of 1 male and 1 female subject both known as drug abusers. Some of the strands were bleached by in-vitro cosmetic treatment. The bleached hair as well as the original hair samples were partly exposed to water or soil prior to further investigations and drug monitoring. The exposure times were 4 weeks or 6 months for water and 6 months for soil. The hair fibers were examined by transmission electron microscope (TEM) and by scanning electron microscope (SEM) investigations. The electron microscope studies confirmed that all experimental conditions had produced morphological alterations in the hair fibers. After exposure to water or to soil for …
The mechanism of epithelial shedding after ischemic damage to the small intestinal mucosa
1979
The intestinal mucosa of the rat was examined by light and electron microscopy 15, 30, 60 and 120 min after complete ligation of the vessel arcades of the proximal jejunum. The characteristic sign of ischemic damage to the small intestinal mucosa and the reason for epithelial shedding is the appearance of membrane enclosed cytoplasmic blebs which arise at the cell base of the enterocytes and detach the epithelium from the basement membrane. This process begins at the tip of the villi before the enterocytes display signs of irreversible damage and progress to the base of the villi with continuation of the ischemia.