Showing papers on "Ultrastructure published in 1980"

Ultrastructure of a magnetotactic spirillum.

Abstract: The ultrastructure of a magnetotactic bacterium (strain MS-1) was examined by transmission, scanning, and scanning-transmission electron microscopy. The organism resembled other spirilla in general cell morphology, although some differences were detected at the ultrastructural level. Electron-dense particles within magnetotactic cells were shown by energy-dispersive X-ray analysis to be localizations containing iron. A non-magnetotactic variant of strain MS-1 lacked these novel bacterial inclusion bodies. A chain of these particles traversed each magnetotactic cell in a specific arrangement that was consistent from cell to cell, seemingly associated with the inner surface of the cytoplasmic membrane. Each particle was surrounded by an electron-dense layer separated from the particle surface by an electron-transparent region. The term "magnetosome" is proposed for the electron-dense particles with their enveloping layer(s) as found in this and other magnetotactic bacteria.

Ultrastructure of the Nonciliated Bronchiolar Epithelial (Clara) Cell of Mammalian Lung: I. A Comparison of Rabbit, Guinea Pig, Rat, Hamster, and Mouse

Abstract: Two morphologic characteristics have been used to define the nonciliated bronchiolar epithelial cell: (1) abundance of agranular endoplasmic reticulum (AER) and (2) numerous membrane-bound ovoid granules. To quantitatively and qualitatively assess the ultrastructural homogeneity of this lung cell type among laboratory mammals used in lung research, we examined tissue from adult male rabbits, guinea pigs, rats, hamsters and mice. Following fixation by airway infusion at constant pressure (30 cm H2O), lungs were processed by a selective embedding technique and bronchioles of known anatomic location were examined by electron microscopy. Nonciliated bronchiolar epithelium of all five species contained ovoid granules and abundant AER. Granules were most abundant in the rat (11.1 ± 8.8 per cell) and least in the hamster (4.4 ± 5.2 per cell). Granules were largest in hamster (0.72 ± 0.25 μm) versus 0.44 μm or less in the other species. Granules were of uniform electron density except in the guinea pig. AER was f...

Ultrastructure of Vascular Smooth Muscle

Abstract: The sections in this article are: 1 Contractile Apparatus 1.1 Filaments 1.2 Dense Bodies and Surface Patches 1.3 Extracellular and Cell-to-Cell Connections: Mechanical Coupling 2 Organelles 2.1 Sarcoplasmic Reticulum 2.2 Surface Vesicles 2.3 Golgi Apparatus and Other Intracellular Organelles 3 Cell Junctions: Electrical and Metabolic Coupling 3.1 Structure 3.2 Function

The axon initial segment as a synaptic site: Ultrastructure and synaptology of the initial segment of the pyramidal cell in the rat hippocampus (CA3 region)

Abstract: The axon initial segments (ISs) of pyramidal cells in the rat hippocampus (CA3 region) were studied by means of light microscopy of Golgi-impregnated material and electron microscopy of random and serial thin sections.

Candida albicans Ultrastructure: Colonization and Invasion of Oral Epithelium

Abstract: The colonization and invasion of various animal oral mucosae by Candida albicans were examined in an organ culture model. Scanning and transmission electron microscopy of the oral epithelium between 12 and 30 h after inoculation with the fungus revealed the morphological relationships between host and parasite. Examination of the fungi in thin sections showed five distinct layers in the cell wall of C. albicans within the epithelium, but changes were evident in the organization and definition of the outer cell wall layers in budding hyphae and in hyphae participating in colonization and invasion of the epithelial cells. Adherence of the fungus to the superficial cells of the oral mucosa appeared to involve intimate contact between the epithelial cell surface and the deeper layers of the fungal cell wall. During invasion a close seal was maintained between the invading hyphae and the surrounding epithelial cell envelope, there being no other evidence of damage to the host cell surface except at the site of entry. Within the epithelial cells there was only occasional loss of cytoplasmic components in the vicinity of the invading hyphae. These findings would suggest that enzymatic lysis associated with the invasive process is localized and that the mechanical support provided by surface adherence and the intimate association between the fungus and the epithelial cell envelope may permit growth of Candida on through the epithelium.

Ultrastructure of intermediate stages in polarity reversal of thyroid epithelium in follicles in suspension culture.

Abstract: Separated thyroid follicles can be maintained in suspension culture in Coon9s modified F-12 medium in 0.5% calf serum. If the serum concentration is raised to 5%, the follicles undergo inversion in 3-5 d. During the process of inversion, epithelial cells can be observed in intermediate stages of polarity reversal. The earliest ultrastructural changes recognized are surface changes in which tight junctions and microvilli appear at the lateral margins of the cell near the medium. Later, changes in the distribution of intracellular organelles occur. The Golgi apparatus shifts towards the end of the cell facing the medium, and lysosomes shift toward the luminal end of the cell. The right junctions and microvilli at the luminal end of the cell disappear sometime after the cytoplasmic organelles rearrange. The luminal colloid disappears only after the surface changes (loss of tight junctions and microvilli) occur at the luminal end of the cell. There appears to be some regulation of the order in which changes occur during polarity reversal of the thyroid epithelial cell.

Ultrastructure of marine teleost gill epithelia: SEM and TEM study of the chloride cell apical membrane.

Abstract: This paper deals with the structure of gill epithelia in the sole, Solea solea, as revealed by transmission and scanning electron microscopy. In this marine teleost the chloride cell and its accessory cell form a cellular complex. Apically the plasma membranes of these cells are loosely juxtaposed, thus forming a leaky epithelium covering a large part of the gill.

Ultrastructure of the small intestine in astrovirus-infected lambs.

Abstract: The ultrastructure of the small intestine of gnotobiotic lambs infected with lamb astrovirus was studied. The virus was observed from 14 to 28 h p.i. in mature columnar epithelial cells covering the apical two-thirds of villi. Crystalline arrays of virus particles with a centre to centre distance of approx. 29 nm were seen in the cytoplasm and virus particles were also observed in apical pits and tubules and in lysosomes. Macrophages containing virus particles in lysosome-like organelles were seen in the lamina propria. Virus particles were released by desquamated cells disintegrating in the gut lumen. Cuboidal cells lining villi appeared from 38 to 70 h p.i., and by 120 h p.i. the villi appeared normal.

Acidophilic granular cells in the epidermis of the brown trout, Salmo trutta L.

Abstract: Acidophilic cells occur in the epidermis of several species of salmonid fish, although their abundance fluctuates considerably between individuals within the same population and at different times during the life cycle. The histology, histochemistry and ultrastructure of an acidophilic, granular celltype in the epidermis of the brown trout, Salmo trutta L., is described. At the light microscope level this cell type is easily distinguished from the large, mucus-secreting, epidermal goblet cells by its acidophilic, proteinaceous secretion. At the ultrastructural level this secretion consists of membrane-bound granules formed by the very active Golgi region. It is argued that the acidophilic, granular cell is not a transformed blood cell but constitutes a normal epidermal component of the brown trout. Possible roles of this cell in the function(s) of the epidermis are discussed.

An ultrastructural study of nerve and glial cells by freeze-substitution

Abstract: The ultrastructure of nerve and glial cells in the cerebral and cerebellar cortices of mice was studied after rapid freezing followed by substitution fixation. The cerebral and cerebellar cortices were frozen by bringing them into contact with a polished pure copper block cooled at a temperature of about −196 ° C. The tissues were fixed and substituted in acetone containing 2–4% OsO4 at −78 ° C for 2–3 days and then prepared for electron microscopy. Tissue fixed by this method displayed the following characteristics. (1) The contour of cells, processes and intracellular membrane systems was smooth. (2) The extracellular spaces were of variable widths. (3) Microtubules were well preserved and were often observed to extend into nerve terminals and to run close to presynaptic membranes. (4) The matrix of cytoplasm and mitochondria was electron dense. Dense granules, possibly binding sites of divalent cations, were often found in the mitochondrial matrix. (5) The plasma membrane of neuronal processes was thicker than that of glial processes. (6) The plasma membranes of nerve fibres and glial processes appeared asymmetrical, the inner leaflet being slightly thicker than the outer leaflet, whereas membranes of cell organelles such as smooth endoplasmic reticulum, Golgi bodies, lysosomes, multivesicular bodies, mitochondria and synaptic vesicles, were symmetrical.

Immunocytochemical Localization of Reserve Protein in the Endoplasmic Reticulum of Developing Bean (Phaseolus vulgaris) Cotyledons

Abstract: The ultrastructure of the storage parenchyma cells of the cotyledons of developing bean (Phaseolus vulgaris L.) seeds was examined in ultrathin frozen sections of specimens fixed in a mixture of glutaraldehyde, formaldehyde and acrolein, infused with 1 M sucrose, and sectioned at-80° C. Ultrastructural preservation was excellent and the various subcellular organelles could readily be identified in sections which had been stained with uranyl acetate and embedded in Carbowax and methylcellulose. The cells contained large protein bodies, numerous long endoplasmic reticulum cisternae, mitochondria, dictyosomes, and electron-dense vesicles ranging in size from 0.2 to 1.0 μm. Indirect immunolabelling using rabbit immunoglobulin G against purified phaseolin (7S reserve protein), and ferritin-conjugated goat immunoglobulin G against rabbit immunoglobulin G was used to localize phaseolin. With a concentration of 0.1 mg/ml of anti-phaseolin immunoglobin G, heavy labeling with ferritin particles was observed ober the protein bodies, the cisternae of the endoplasmic reticulum, and the vesicles. The same structures were lightly labeled when the concentration of the primary antigen was 0.02 mg/ml. Ferritin particles were also found over the Golgi bodies. The absence of ferritin particles from other organelles such as mitochondria and from areas of cytoplasm devoid of organelles indicated the specificity of the staining, especially at the lower concentration of anti-phaseolin immunoglobulin G.

Electron microscopy in the diagnosis of neuroblastoma.

Abstract: I review the accumulated knowledge regarding the electron microscopy of neuroblastic tumors using a retrospective study of 13 primarily small cell neoplasms for which the diagnosis of a neuroblastic tumor (neuroblastoma, ganglioneuroblastoma, ganglioneuroma) was either considered or eventually established. A fine fibrillary background, even if focally distributed by light microscopy and seemingly not recovered in the thick sections, correlated with the presence ultrastructurally of neuritic processes bearing dense core ("neurosecretory") granules and lucent vesicles. In three cases without any fibrillary background by light microscopy, granule-bearing processes were not found by electron microscopy, and different diagnoses were subsequently established for two of those cases. From the standpoint of diagnosis, the sampling error normally introduced in ultrastructural examinations has not been reported to be a significant problem, nor was it in the present cases. Therefore, in supporting a light microscopic diagnosis of neuroblastoma, neuritic processes containing dense granules with or without lucent vesicles should be documented. Neuroblastic tumors with evidence of maturity, ie, ganglion cell differentiation, had the best developed morphologic features by both forms of microscopy. Schwann cells were observed in four cases, including one neuroblastoma. The presence of these cells by electron microscopy, although absent by light microscopy, may reflect an early phase of tumor maturation.

Ultrastructural changes in the small intestine of zinc deficient rats.

Abstract: In normal rats changes in the enterocytes that appear to be associated with physiological cell death were found. They were confined to the villous tip and included fragmentation of the microvilli and increased electron density of the cytoplasm with morphological alterations of the organelles. Acute severe zinc deficiency in young rats results in degenerative changes in the enterocytes and microvillous damage which is not confined to the villous tip. Increased numbers of apoptotic bodies as a result of cell death are found. The enterocyte lesions differed from cell death preceding normal desquamation. There were no significant changes in Paneth cell ultrastructure. These results were compared with the ultrastructural findings reported in patients with Acrodermatitis Enteropathica.

Ultrastructure of the septum in candida-albicans

Abstract: The ultrastructure of the septum in the mycelial phase of the dimorphic fungusCandida albicans has been studied both in thin sections of fixed material and in shadow casts of the chemically purified chitinous wall layer. The septum has a 25-nm central micropore which would not allow the passage of nuclei or mitochondria, thus delimiting these organelles within the mycelial compartments without preventing cytoplasmic continuity.

Ultrastructural and morphometric study of the Langerhans cell in the normal human exocervix.

Abstract: The gross morphology, density, distribution and ultrastructure of the Langerhans cell of the normal human exocervix were investigated Two standardized zinc-iodide-osmium (ZIO) procedures were applied to epithelial sheets as well as to tissue samples processed for both light and electron microscopy Conventional electron microscopical techniques were also used The epithelial sheet preparation allowed the visualization of the whole profile of the Langerhans cell It was found that the number of cell processes and the degree of their branching varied greatly from one cell to another The cells were tentatively grouped into five types and it is suggested that they represent different degrees of cell activity The cells appeared unevenly distributed, but with a preferential location around the external os In the three cases studied the cell density averaged 83 LC/mm2 The ultrastructural study revealed the classical fine structure of the Langerhans cell The cell processes and their branches contained all the organelles found in the perikaryon, including Golgi complexes and Langerhans cell granules The two ZIO procedures revealed that the complex inner organization of the granule does not differ from that in the epidermal Langerhans cell It is concluded that the Langerhans cell is a constant component of the normal human exocervix

The ultrastructure of rapid-frozen, substitution fixed parotid gland acinar cells of the mongolian gerbil (Meriones meridianus).

Abstract: The ultrastructure of gerbil parotid gland acinar cells studied by rapid freezing in liquid nitrogen and freeze-substituting with OsO4 was similar in general to conventionally prepared tissue, but different in several aspects. Acceptable preservation was limited to about 10 microgram of the surface; the secretory granule membrane was a single dense line, while all others were trilaminar; the dense-cored secretory granule had a rim of low density which was homogeneous; there were many continuous profiles between the Golgi lamellae, vesicles, and vacuoles; and mitochondria were long and arborized.

Supraependymal macrophages of third ventricle of hamster: Morphological, functional and histochemical characterization in situ and in culture

Abstract: Supraependymal cells (SECs) of the young hamster's third ventricle have been examined by scanning and transmission electron microscopy. Of special interest were cells with the surface morphology and ultrastructure of macrophages, which were found in largest numbers in 12--15-day-old females and males. In the ciliated areas SECs are generally smooth and rounded; in nonciliated areas, they frequently have surface ruffles, blebs and microprocesses. SECs were frequently seen to be dividing or fusing. The macrophage-like cells are characterized by prominent Golgi zones and numerous large vacuoles, and frequently contain inclusions in their cytoplasm which resemble intraventricular cell processes, cytoplasmic protrusions from ependymal cells and cellular debris. We have demonstrated that supraependymal macrophage-like cells phagocytose latex beads injected into the ventricles of the brain. Supraependymal cells from 12-day-old hamsters were grown in tissue culture. Phagocytic, cytochemical and surface ultrastructural studies were then done sequentially on the same population of cells. These studies revealed the cells to be actively phagocytic as well as strongly esterase positive and peroxidase negative, consistent with their classification in the macrophage/monocyte category. The surface ruffles, ridges and microprocesses were also characteristic of the SECs seen in situ with scanning electron microscopy and of the macrophages cultured from the peritoneum and peripheral blood of the same hamsters. On the basis of cellular morphology, cytochemical staining characteristics and functional response to exposure to foreign particles both in situ and in cell culture, we have demonstrated that supraependymal cells of the third ventricle of the hamster are phagocytes that resemble cells of the macrophage/monocyte line. It is suggested that they constitute a resident macrophage system of the ventricles of the brain.

Ultrastructural localization of enkephalin-like immunoreactivity in the rat adrenal medulla.

Abstract: The PAP method was applied to adrenomedullary cells to demonstrate the subcellular localization of ELI. The labeled cell-groups were identified from flat-embedded virbratome sections by light microscopy. Electron microscopy showed that the precipitate was associated with the storage granules of the cells. The number of labeled granules varied greatly from cell to cell. In cells corresponding to those showing heavy staining by light microscopy, all the granules were stained with precipitate. It is suggested that the peptide responsible for the ELI might be released together with the catecholamines.

The cat locus coeruleus. Light and electron microscopic study of the neuronal somata.

Abstract: The neuronal cell bodies of the locus coeruleus (LC) and subcoeruleus (SC) of the cat were investigated using Nissl and Golgi preparations, and electron microscopy. On the basis of morphological criteria — size and shape of cell body, branching pattern of dentrites, distribution of cytoplasmic organelles and number of axosomatic synapses — four types of neuronal perikarya were recognized in each region: medium-sized, small-sized and two groups of intermediate-sized neurons. The medium-sized neurons (30–50 μm) had an elongated cell body, thick dendrites with a moderate number of branchings, abundant organelles arranged in concentric rings around the nucleus and a moderate number of axosomatic synapses. They were found throughout the LC and SC and most probably correspond to the larger class of catecholaminergic neurons demonstrated by fluorescence histochemistry. The small neurons (10–25 μm) were also seen in both LC and SC and are believed to represent non-monoaminergic local interneurons. They displayed sparsely branching dendrites and a thin rim of cytoplasm containing few organelles. In the SC, some of these small cells occurred in closely associated pairs. Ultrastructural analysis of such pairs revealed a close apposition (80–100 A) of the cell membranes for long distances (up to 10 μm) and a narrowing of the intercellular space (30–40 A) at some discrete points, perhaps indicative of an electrical interaction. The intermediate-sized neurons exhibited some regional morphological differences, but two distinct subgroups could be distinguished. One was characterized by a low number of axosomatic synapses, while the other exhibited a high number of such contacts. It may be assumed that the two subgroups of intermediate-sized neurons comprise catecholaminergic and indolaminergic neurons.

Ultrastructure of serotonin-containing cells in the pineal organ of Lampetra planeri (Petromyzontidae).

Abstract: The ultrastructure of the “cells containing residual bodies” (Collin, 1969) was investigated in the pineal organ of Lampetra planeri. These cells are characterized by their indoleamine metabolism (Meiniel, 1978; Meiniel and Hartwig, 1980). Morphologically, they belong mainly to two types: (1) a photoreceptor cell type, and (2) a pinealocyte cell type. The first type is present in the pineal sensory epithelium and in the atrium, while the second is observed in the deep part of the atrium. Intermediate cell types are rare. All these cells are characterized by the presence of voluminous dense bodies, the 5-HT-storing structures, in their cytoplasm.

The ultrastructure of the protonephridial tubules of the freshwater planarian Bdellocephala brunnea.

Abstract: The protonephridial flame cell of the freshwater planarian Bdellocephala brunnea was studied by electron microscopy. This basketlike cell with luminal cilia and fenestrae is known as a cyrtocyte. Careful examination revealed the actual continuity of the fenestrae over the surface of the cell and the microvillous nature of thin cytoplasmic rods composing the fenestrae. On the basis of these findings, a new interpretation was given for the threedimensional configuration of a single cell: this cell is essentially stellate in shape, with several irregular cytoplasmic processes adjoining one another, thus bearing a basic resemblance to the podocyte of a mammalian renal corpuscle. The cytoplasmic features strongly suggest its great capability of reabsorbing substances from the filtrate and of carrying out intracellular digestion. Some additional structural specialization of the fenestra, serving for enlargement of the filtration surface, was observed.

Ultrastructure of the tastebuds of the red-eared turtle, Chrysemys scripta elegans.

Abstract: The fine structure of the turtle tastebud has been examined by light, transmission, and scanning electron microscopy. It contains five types of cells on the basis of their cytological features, designated types 1,2,3,A, and B. Types 1, 2, and 3 reach the taste pore, whereas types A and B are located basally. The type 2 cell has access to the tongue surface, i.e., the site of gustatory stimuli, and also synapses onto afferent nerves; it probably is a gustatory receptor cell and corresponds to the so-called "light" cell observed in other vertebrate tastebuds. Some cells may be differentiating. In support of this hypothesis, light microscopic autoradiography shows that postmitotic cells occur in the tastebuds within 24 hours after administration of H3 -thymidine. The tastebuds of the turtle are similar to those of other vertebrates described electron-microscopically.

Some aspects of the ultrastructure of Gotocotyla secunda and Hexostoma euthynni.

Abstract: The ultrastructure of the spermatozoon, the protonephridia, the intestine and the tegument of Gotocotyla secunda (Monogenea, Gotocotylidae) and of the intestine of Hexostoma euthynni (Monogenea, Hexostomatidae) is described The "connecting cells" in the intestine of at least some Monogenea show secretory activity and are possibly involved in extracellular digestion Sloughing of whole haematin cells appears to be common and may be an important component in the digestive process Flame cells appear to be a very conservative element and their more or less identical structure in all major groups of parasitic platyhelminths indicates that parasitic platyhelminths have originated from one or a few closely related groups of freeliving Turbellaria with the same type of flame cell

The Ultrastructure of the Pre-Ovulatory Human EGG Fertilized in Vitro

Abstract: Preovulatory eggs in cumulus were inseminated in vitro with washed spermatozoa which had been preincubated for 1.5 hours. After 3 hours, three eggs were processed for electron microscopy and each was sectioned serially from pole to pole. In the two eggs which had been fertilized, the expanded chromatin of the fertilizing sperm head and the chromatin of the ovum were almost completely surrounded by a developing pronuclear envelope. In one of the penetrated eggs the developing male pronucleus and associated midpiece and sperm tail were located within an incorporation cone. The surface of the cone was free of microvilli but contained a zone of microfilaments immediately beneath the plasma membrane. A similar zone of microfilaments was present beneath the advancing surface of the extruding second polar body (PB2) which was connected to the ovum by an interbody and microtubules of the meiotic spindle. Cortical granules were completely absent from the fertilized eggs but were present in the unfertilized egg. PB2 contained a nucleus at a stage of development similar to that of the early pronuclei.