Search results for "Ultrastructure"
showing 10 items of 224 documents
Damage in Escherichia coli Cells Treated with a Combination of High Hydrostatic Pressure and Subzero Temperature
2007
ABSTRACT The relationship between membrane permeability, changes in ultrastructure, and inactivation in Escherichia coli strain K-12TG1 cells subjected to high hydrostatic pressure treatment at room and subzero temperatures was studied. Propidium iodide staining performed before and after pressure treatment made it possible to distinguish between reversible and irreversible pressure-mediated cell membrane permeabilization. Changes in cell ultrastructure were studied using transmission electron microscopy (TEM), which showed noticeable condensation of nucleoids and aggregation of cytosolic proteins in cells fixed after decompression. A novel technique used to mix fixation reagents with the c…
Adhesive papillae ofAscidia malacaswimming larvae: investigations on their sensory function
1999
Summary Swimming larvae of Ascidia malaca bear, in the anterior region of cephalenteron, three adhesive papillae through which they can attach to a substratum prior to metamorphosis. The ultrastructural investigations described in the present work have mainly revealed the presence of three cell types constituting the papillae: (a) collocytes, (b) axial columnar cells, (c) sensory cells. Collocytes, whose ultrastructure is typical of secretory cells, form the adhesive secretion. The ultrastructural observations of the axial columnar cells are insufficient to explain their function. Probably this cell type plays a supporting role though some sensory function cannot be excluded due to the pres…
Electron microscopic localization of nitric oxide I synthase in the organ of Corti of the guinea pig
1997
Nitric oxide synthase (NOS) activity has been detected previously in the mammalian cochlea at a light microscopic level. Here we present results of electron microscopic analysis for post-embedding immunoreactivity of neural-type NOS I in the cochlea of the guinea pig. Strong enzyme immunoreactivity was identified in the cytoplasm of inner and outer hair cells. Gold-labeled NOS I antibodies were mainly located in electron-dense areas of the cytoplasm, whereas electron-lucent regions of the receptor cells were nearly free from any immunoreactivity. In both types of hair cells anti-NOS I antibodies were also visible in the cuticular plates, hair bundles and nuclei. Further ultrastructural anal…
Storage Diseases: Diagnostic Position
2013
Storage diseases are metabolic multiorgan conditions, which may be divided into lysosomal and nonlysosomal diseases. Disorders of the lysosomal type require electron microscopy for morphological diagnosis. It is the metabolic substrate that determines involvement of the cell type or organ in the individual storage disease, allowing extracerebral biopsies, for instance, in the neuronal ceroid-lipofuscinoses (NCL). A hierarchy of tissues biopsied for diagnosis can be based on easy accessibility: blood lymphocytes, skin, conjunctiva, rectum, skeletal muscle. Lysosomal diseases are divided into vacuolar and nonvacuolar ones. NCL display variegated ultrastructural patterns. Drugs may induce lyso…
Electron microscopic demonstration of intracelluar promethazine accumulation sites by a precipitation technique: application to the cerebellar cortex…
1996
A method is described that allows electron microscopic identification of the phenothiazine neuroleptic promethazine after supravital intracardiac injection of high drug concentrations (greater than or equal to 3 %). The cerebellar cortex of the mouse was used for the investigation. This procedure is based on simultaneous fixation of drug and tissue by immersion in a paraformaldehyde-glutaraldehyde solution with the addition of phosphomolybdic acid. The electron microscopic investigation revealed that the drug could easily be identified as an electron-dense precipitate. Subpopulations of neurons exhibited a higher affinity for the drug than others, but no preference for any nerve cell type …
Mesadenes maturation and its hormonal control in the milkweed bug, Oncopeltus fasciatus
1993
Abstract Adult maturation of the mesadenia was examined by electron microscopy. The glandular epithelium exhibits only one cell type with a polarity along the haemocoel-lumen axis. In newly emerged males, the glands show little signs of secretory activity although the narrow lumen contains some material. Dramatic changes commence at day 2. The rER increases drastically, and at day 3 cisternae of the rER are considerably distended and include a fine granulated product. The lumen of the gland widens greatly and stores material of the same appearance as in the rER inclusions. The mode of the secretory process is not clear since membrane bound vesicles are not formed. SDS-PAGE of the secretion …
Proteinaceous Surface Layers ofArchaea: Ultrastructure and Biochemistry
2014
The cell walls of the Archaea are composed of different polymers such as glutaminylglycan, heterosaccharide, methanochondroitin, pseudomurein, protein, glycoprotein, or glycocalyx. The S-layer glycoprotein of Halobacterium salinarum was the first glycoprotein discovered in bacteria and archaea. Initially, the novel cell wall structures were viewed as curiosities, and their taxonomic significance was not realized until the concept of the Archaea was published. At this time, the results of cell wall studies supported the new view of the phylogeny of the Bacteria and Archaea. Many archaea possess proteinaceous surface layers (S layers), which form two-dimensional regular arrays. The chemical s…
The ultrastructure of the thread-hairs on the cerci of the cockroach Periplaneta americana L.: The intermoult phase
1976
The structure of the thread-hairs on the cerci of the cockroach Periplaneta american during the intermoult phase has been investigated by scanning and transmission electron microscopy. The present study demonstrates that to each thread-hair belong one sensory cell, two glial cells, and three enveloping cells. The data indicate that: (a) the inner glial cells, which may have a trophic function, sends fingerlike processes into the cytoplasm of the senory cell body; (b) the internal enveloping cell forms the dendritic sheath; (c) the middle enveloping cell corresponds to the trichogen cell and the external enveloping cell to the tormogen cell; (d) the outer dendritic segment terminates in a ca…
Microtubules and cell shaping in the mesophyll ofNigella damascena L.
1993
Cell shaping in the mesophyll ofNigella damascena was investigated with the aim of determining the origin of the arm-like protrusions, which are characteristic of, e.g., arm-palisade cells. It was found that hoops of cell wall were deposited during the early stages of cell expansion. The hoops were interconnected, thus embracing the cells with a wide-meshed net of local wall reinforcement. The pattern of wall deposition in the extra-cellular matrix correlated with a pattern of bands of microtubules in the cortical cytoplasm of the cells. During lateral expansion bulges were forced through the comparatively thin walls of spaces between the meshes, giving rise to the arm-like protrusions. Aft…
Cell shaping and microtubules in developing mesophyll of wheat (Triticum aestivum L.)
1990
Differentiated mesophyll cells ofTriticum aestivum (cv. Star) exhibit a lobed outline resembling tube-shaped balloons with almost regularly spaced constrictions. It was shown that these constrictions are probably the result of hoops of wall reinforcements laid down during early stages of cell expansion. It appears that these hoops prevent expansion in the corresponding regions and thus give rise to the peculiar cell shape. The comparatively thin cell walls of the bulges are uniformly reinforced after the lobed shape is established. By using immunofluorescence techniques a change in the pattern of cortical microtubule arrangement was observed which corresponded to the pattern of cell wall de…