bluuebunny/crossref_metadata_2025 huggingface dataset:
Analysis of STEM micrographs of thick objects
Authors: Golladay S.
Published: June 2020

The theory of multiple scattering has been worked out by Groves and comparisons have been made between predicted and observed signals for thick specimens observed in a STEM under conditions where phase contrast effects are unimportant. Independent measurements of the collection efficiencies of the two STEM detectors, calculations of the ratio σe/σi = R, where σe, σi are the total cross sections for elastic and inelastic scattering respectively, and a model of the unknown mass distribution are needed for these comparisons. In this paper an extension of this work will be described which allows the determination of the required efficiencies, R, and the unknown mass distribution from the data without additional measurements or models. Essential to the analysis is the fact that in a STEM two or more signal measurements can be made simultaneously at each image point.
Intracellular calcium distribution map and chemical shift of neurons examined by computer controlled electron probe X-ray microanalyser
Authors: Onozuka Minoru , Sugaya Eiichi , Sugaya Aiko , Usami Masayoshi
Published: June 2020

The role of divalent cations, particularly of calcium, has gained increasing interest as a charge carrier and in processes such as regulation of enzymatic activities, in secretions of humoral transmitters and initiation of muscle contraction. The role of calcium has become very important in manifesting the bursting activity of neurons by various electrophysiological techniques, especially by voltage clamping. The distribution of calcium compared with the ultrastructure of nerve cells, however, has not been widely investigated. Analysis by the electron probe X-ray microanalyser(EPXMA) makes this type of research easier. To determine the relationship between calcium localization within the neuron and cellular function, we tried to make an intracellular calcium distribution map of the normal state and that during bursting activity by the computer controlled EPXMA. We also detected the chemical shift between the different states of cellular function caused by the intracellular calcium binding state.
Decoration of specific sites on freeze-fractured membranes
Authors: Gross H. , Moor H.
Published: June 2020

Fracturing under ultrahigh vacuum (UHV, p ≤ 10-9 Torr) produces membrane fracture faces devoid of contamination. Such clean surfaces are a prerequisite foe studies of interactions between condensing molecules is possible and surface forces are unequally distributed, the condensate will accumulate at places with high binding forces; crystallites will arise which may be useful a probes for surface sites with specific physico-chemical properties. Specific “decoration” with crystallites can be achieved nby exposing membrane fracture faces to water vopour. A device was developed which enables the production of pure water vapour and the controlled variation of its partial pressure in an UHV freeze-fracture apparatus (Fig.1a). Under vaccum (≤ 10-3 Torr), small container filled with copper-sulfate-pentahydrate is heated with a heating coil, with the temperature controlled by means of a thermocouple. The water of hydration thereby released enters a storage vessel.
UHV freeze-facturing and image processing applied to the purple membrane
Authors: Kuebler O. , Gross H.
Published: June 2020

The complementarity of periodic features on the fracture faces of the yeast plasmalemma has been established to a resolution 20Å by ultrahigh vaccum (UHV, p≤10-9Torr) freeze-fracturing at -196°C and subsequent digital image processing. The structural record is considered reliable because of the one-to-one correspondence of volcano-like practicles on the plasmic fracture face (PF) and of ring-like depressions on the extraplasmic face (EF). The PF-particles were tentatively related to intrinsic proteins. Nevertheless experience with specimens which are biochemically and structurally more well defined than yeast appears indispensable in learing how to interpret the structural record. For this purpose the purple membrane of Halobacterium halobium appeared attractive.
Influence of cryofixation procedures on organization and partition of intramembrane particles
Authors: Lefort-Tran M. , Gulik T. , Plattner H. , Beisson J. , Wiessner W.
Published: June 2020

Three freeze-fracture procedures have been used to study organization and partition of intramembrane particles in plasma membranes of wild type Parameciumand plasma membranes of Chlamydobotrys stellata. In the first procedure, the samples were prefixed with glu- taraldehyde, incubated with 25 t glycerol and frozen in liquid Freon 22 (C). In two other procedures, namely spray freezing (SF) and sandwich freezing (S), the samples were very rapidly frozen without any pretreatment. Good cryofixation of unfixed specimens in the latter two cases is acheived by a four to ten times faster freezing rate as compared to conventional freezing. Paramecia plasma membranes display a conventional polarity (P face more particulate that E face). Xhe trichocyst site (Fig. 1 b) is composed of a large (300 nm) outer ring of c.a. 80 Å particles and of a central rosette of 8 c.a. 150 Å particles.
Photoreceptor disk membrane substructures by means of the complementary freeze-fracture-replica methods
Authors: Tonosaki A. , Yamasaki M. , Washioka H. , Mizoguchi J.
Published: June 2020

A vertebrate disk membrane is composed of 40 % lipids and 60 % proteins. Its fracture faces have been classed into the plasmic (PF) and exoplasmic faces (EF), complementary with each other, like those of most other types of cell membranes. The hypothesis assuming the PF particles as representing membrane-associated proteins has been challenged by serious questions if they in fact emerge from the crystalline formation or decoration effects during freezing and shadowing processes. This problem seems to be yet unanswered, despite the remarkable case of the purple membrane of Halobacterium, partly because most observations have been made on the replicas from a single face of specimen, and partly because, in the case of photoreceptor membranes, the conformation of a rhodopsin and its relatives remains yet uncertain. The former defect seems to be partially fulfilled with complementary replica methods.
Simultaneous observations of immunolabeled frozen sections in lm and em
Authors: Tokuyasu K. T. , Slot J. , Singer S. J.
Published: June 2020

Immunofluorescent microscopy is more suitable for the analysis of a large number of cells, often greater in the sensitivity for the detection of antigens, and more readily applicable for the identification of multiple antigens than immunoe1ectron microscopy. For combining these features of fluorescent microscopy with the superior resolution of electron microscopy, we attempted to observe the same immunolabeled ultrathin frozen sections with both light and electron microscopy.

Ultrathin frozen sections of rat pancreas fixed in a mixture of 2% formaldehyde and 0.2% g1utaraldehyde for 1 hr at 4°C were first immunostained with rabbit anti-rat amylase antibodies, then very lightly with ferritin-goat anti-rabbit IgG conjugates and heavily with rhodamine-goat anti-rabbit IgG conjugates. For light microscopic observation, grids were suspended underneath the cover glass with a very thin layer of 50-90% glycerol and the cover glass was separated from the slide glass by a spacer to avoid the contact of the grid with the slide glass. After the light microscope observation, the grids were floated on 0.1 M phosphate buffer by dissolving glycerol into the buffer and processed for electron microscopy.
Organization of immunoglobulin genes
Authors: Brack CH. , Lenhard-Schuller R. , Traunecker A. , Tonegawa S.
Published: June 2020

Recent DNA-RNA hybridization experiments suggested that the genes coding for variable (V gene) and constant (C gene) parts of immunoglobulin molecules are separate in embryonic mouse DNA, whereas in lymphocyte DNA they are close together, implying a somatic rearrangement process of the two genes during lymphocyte differentiation. To study mechanisms involved in the organization and expression of Ig genes at a molecular level, we have been cloning DNA fragments containing Ig light chain genes from early embryonic cells and from myeloma cells. We here report electron microscopic characterization of three cloned DNA fragments: two clones from embryonic DNA carrying V gene (Ig 99) and C gene sequences (Ig 25), and one clone from myeloma DNA carrying both V and C genes (Ig 303).

R-loop mapping. The purified DNA fragments were hybridized to Ig mRNA (isolated from λ type light chain producing myeloma cells) under conditions of R-loop formation. Measurement of the position and extension of the R-loops allowed us to localize the regions homologous to the Ig mRNA and to construct a preliminary map of the DNA fragments.
Electron microscope studies of the isolated dna fragments containing biotin genes of escherichia coli k12
Authors: DasGupta C.K. , Samanta H. , Guha A.
Published: June 2020

The genes coding for the biotin biosynthetic enzymes, bioABFCD are located at 17 min of the linkage map of EL coli K12 (Bachman, et al. Bact. Rev. 40: 116, 1976). It was shown that the bioA gene is oriented anticlockwise and the bioBFCD genes are oriented clockwise in the EL coli map, with the bio regulator region lying in between them (Guha et al. J. Mol. Biol. 56: 53, 1971). The study of the control elements of this divergently oriented operon at the molecular level is important for understanding the various intriguing mechanisms of gene expression in bacteria. In the present work, the electron microscopic characterization of the entire biotin genes and its regulator segment isolated after cleaving a biotin transducing phage DNA by restriction endonucleases, is described. The isolated biotin DNA fratments were subsequently recombined with the colEI DNA to isolate a colEl-biotin DNA hybrid. The present report also includes a portion of the study of this cloned plasmid chimera in a biotin auxotroph.
Existence of DNA in yeast microbodies
Authors: Osumi Masako , Nagano Misuzu , Kazama Hiroko
Published: June 2020

We have found that microbodies appeared profusely together with a remarkable increase in catalase activity in normal alkane-grown cells of hydrocarbon-utilizing Candida yeasts, and that the microbodies multiplied by division in these cells. These features of Candida yeasts seem to provide a useful model system for studies on the biogenesis of the microbody. Subsequently, we have succeeded in isolation of Candida microbodies in an apparently native state, as judged biochemically and morphologically. The presence of DNA in the purified microbody fraction thus obtained was proved by the diphenylamine method. DNA molecule of about 15 urn in contour length was released from an isolated microbody. The physicochemical analyses of the microbody DNA revealed that its buoyant density differed from nuclear and mitochondrial DNAs. All these results lead us to the possibility that there is a novel type of DNA in microbodies.
Morphology of escherichia coli ribosomes as obtained by high resolution shadow cast
Authors: Tesche B. , Tischendorf G.W. , Stöffler G.
Published: June 2020

All components (54 proteins and 3 RNA molecules) of the E. coli ribosome have been identified and characterized by biochemical and biophysical means. The morphology of the ribosome and the structural arrangement of its components, however, is not yet unequivocally known. The reasons for this are that crystal arrangements could not be obtained and that the different preparations of single particles remain invariant; and that holds for different laboratories as well.

We applied a preparation which has been demonstrated to be most gentle and hence most structure-preserving; that is, freeze-drying with shadow casting at -150°C. Furthermore, the evaporator is of such design that it produces very little heat and renders a thin, fine-grained tungsten layer. An electron optical resolution of 6 Å can be achieved. Fig. 1 shows a micrograph of a typical shadowgraph obtained with 70S ribosomes from which we attempt to derive a three-dimensional model of the ribosome.
Cytochemical and ultrastructural studies on sexual dimorphism of rat liver peroxisomes
Authors: Ohkawa Kin-ichi , Suzuki Yasuhiro
Published: June 2020

Considerable biochemical evidence has been obtained in connection with sexual differences in the activity of hepatic enzymes such as steroid metabolizing enzymes and catalase, and in the lipid composition of microsomal membranes. In addition to these biochemical findings, a variety of chemicals are also known to induce sex-dependent hepatocellular alterations. Since attempts have apparently not been made to obtain evidence of hepatic sexual dimorphism, we designed the present experiments and did obtain evidence for sexual dimorphism of hepatic peroxisomes.

Throughout the experiments we used the liver from both male and female Wistar rats. The conditions of the rats were as follows. Three ∽ five month old sexually mature rats of both sexes. Two ∽ three week old sexually immature rats of both sexes. Rats of both sexes that were gonadectomized and ovariectomized at age 23 days and killed two months later. Some of these gonadectomized rats were killed 7 months later.
Cytofunctional analysis of conveyer system in glandular cells relating to chemical composition of secretion product
Authors: Zufahov K.A.
Published: June 2020

Since Hirsch /1963/ has described the intracellular conveyer ha protein-secreting cells the oiological science was enriched by many new findings.Comparative studies of synthetic and secretion processes both in endocrine and exocrine glands undertaken in our laboratory have demonstrated that a conveyer system is also preserved in cells secreting non-protein product.The obtained data have shown that there may oe following conveyer systems relating to chemical composition of secretion product: 1.intracellular conveyer of protein-secreting cells; 2.mucus-secreting cells; 3.lipoid /steroid/secreting cells; 4.mineral product /H+-ions,Na+,K+-salts/secreting cells.

Using methods of differential centrifugation for the isolation of subcellular structures comprising synthetic conveyer in glandular cells we have found that protein being synthesized initially in the rough endoplasmic reticulum and transported to the Golgi underwent not only simple condensation process but also essential qualitative alterations /Fig.1/.As a rule,this is accompanied by the splitting off additional amino-acid residue from a peptide molecule,that is,the conversion of prohormone into active hormone.
The ultrastructure of acinar cells in the external orbital gland of young and old male rats
Authors: Carriere R.
Published: June 2020

The external orbital gland of the albino rat exhibits both sexual dimorphism and histological age changes. In males, many cells attain a remarkable degree of polyploidy and an increase of polyploid cell number constitutes the major age change until young adulthood. The acini of young adults have a small lumen and are composed of tall serous cells. Subsequently, many acini acquire a larger lumen with an irregular outline while numerous vacuoles accumulate throughout the secretory cells. At the same time, vesicular acini with a large lumen surrounded by pale-staining low cuboidal diploid cells begin to appear and their number increases throughout old age. The fine structure of external orbital glands from both sexes has been explored and in considering acinar cells from males, emphasis was given to the form of the Golgi membranes and to nuclear infoldings of cytoplasmic constituents.
An ultrastructural method for the study of cell viability using ruthenium red
Authors: Féridoun Babaï
Published: June 2020

Ruthenium Red (RR), a colored inorganic dye, has been used in electron microscopy to stain and visualize the glycoproteins of the cell coat. It has an average particle size of 1.13 nm and does not seem to penetrate the intact plasma membrane. Consequently the cytoplasmic and nuclear components of viable cells are not stained with this electron-opaque marker.

We have used these properties of RR to develop a method for the study of abnormal permeability of damaged cell membrane and to stain nonviable cells. Under certain conditions, RR stains the cytoplasm of damaged cells in suspension (Figs. 1,2) or in culture in situ (Figs. 3-5). The stained (permeable) cells are easily visualized under the light and electron microscope.

Cell suspension of an ascitic Novikoff Hepatoma and cell culture from a Rhabdomyosarcoma were utilized for this study.
Electron microscopic cytochemistry of functional groups in the lumenal plasma membrane of the rabbit urinary bladder
Authors: Seguchi H. , Okada T. , Ogawa K.
Published: June 2020

In order to fill gap between the morphological findings and the biochemical ones on the plasma membrane, it is of great value to demonstrate the macromolecular structure ultracytochemically in the plasma membrane. In the present investigation the routine morphological studies, the freeze-etching procedure, the negative staining, the ultracytochemical demonstration of sulfhydryl (SH) groups and the performic acid (PF)-phosphotungstic acid (PTA) reaction (PFP reaction) were performed on intact or isolated lumenal plasma membranes of the rabbit urinary bladder.

Glutaraldehyde-fixed intact or isolated lumenal plasma membranes were used. To prepare the isolated lumenal plasma membrane, bladders were excised and distended for 10 min with 0. 02 M sodium thioglycollate, pH 7. 4, at 4°C after washing with 0. 01M HEPES buffer, pH 7. 4. The pooled solution from bladders was centrifuged at 3, 000 xg for 10 min.
Organization of tight junctions in the choroid plexus epithelium
Authors: Van Deurs B. , Koehler J. K.
Published: June 2020

The choroid plexus epithelium constitutes a blood-cerebrospinal fluid (CSF) barrier, and is involved in regulation of the special composition of the CSF. The epithelium is provided with an ouabain-sensitive Na/K-pump located at the apical surface, actively pumping ions into the CSF. The choroid plexus epithelium has been described as “leaky” with a low transepithelial resistance, and a passive transepithelial flux following a paracellular route (intercellular spaces and cell junctions) also takes place. The present report describes the structural basis for these “barrier” properties of the choroid plexus epithelium as revealed by freeze fracture.

Choroid plexus from the lateral, third and fourth ventricles of rats were used. The tissue was fixed in glutaraldehyde and stored in 30% glycerol. Freezing was performed either in liquid nitrogen-cooled Freon 22, or directly in a mixture of liquid and solid nitrogen prepared in a special vacuum chamber. The latter method was always used, and considered necessary, when preparations of complementary (double) replicas were made.
Oncornavirus assembly at the cell surface revealed in replicas of freeze-dried cells
Authors: Demsey Anthony , Stackpole Christopher W.
Published: June 2020

The murine leukemia viruses are type-C oncornaviruses, and their release from the host cell involves a “budding” process in which the newly-forming, RNA-containing virus core becomes enveloped by modified cell surface membrane. Previous studies revealed that the released virions possess a dense array of 10 nm globular projections (“knobs”) on this envelope surface, and that these knobs contain a 70, 000 MW glycoprotein (gp70) of viral origin. Taking advantage of this distinctive structural formation, we have developed a procedure for freeze-drying and replication of intact cells which reveals surface detail superior to other surface replica techniques, and sufficient to detect even early stages of virus budding by localized aggregation of these knobs on the cell surface.

Briefly, cells growing in monolayer are seeded onto round glass coverslips 10-12 mm in diameter. After a period of growth, cells are fixed in situ for one hour, usually with 1% OsO4 in 0. 1 M cacodylate buffer, and rinsed in distilled water.
Bodies in the chloroplasts of sugar-beet infected by mosaic virus
Authors: A Tulegenov Tursunbai
Published: June 2020

Beet mosaic virus (Potyvirus group ) induced two types of inclusion bodies in the chloroplasts of the cells of epidermal tissue of sugar-beet. The crystalline type of inclussions having six-edged form is the largest one and it is of the higher electron density(Pig. 1. ). The size of their edges is depended on the angle section and it is changing from 0, 33μ to 1, 5μ. The quantity of them is constant. Comparasion of large number of sections gives us the oppotunity to suppose that these inclusions in three-dimensional measuring present itselves in a form of six-edged prism, oriented along the length of the chloroplasts. Exceptions may also take place. There are met crystalls with 4-5 edges.

The largest inclusion bodies copy the form of the external membrane of chloroplasts and have rounded forms or protuberant edges. (Fig. 2. ). Crystals are devided from the stroma of chloroplast with the help of single membrane (M) placing near the edges. In large magnifications in longitudinal sections of the crystals a striation(with periodicity of 7, 4 nm) is revealed. In cross sections they have lattice structure.
Lytic activity of the plasmalemma and its derivatives in plant cells
Authors: Belitser N. V.
Published: June 2020

Ultrastructural, cytochemical and densitometrical investigation carried out on suspension culture cells of Haplopappus gracilis, protoplasts isolated from leaf parenchyma cells of Nicotiana tabacum, root meristem, root cap cells and young leaves of Hordeum seedlings revealed a pronounced lytic capacity of plasmalemma evaginations and invaginations. In cultivated cells plasmalemma outgrowths into the cell walls exhibited high acid phosphatase activity; presumably, they are important for separation of the aggregated cells. The lytic activity of plasmalemma infoldings seen in cultivated cells increased if the cells were transferred to a medium lacking carbohydrate. In starved cells plasmalemma evaginations protruding into the wall isolated wall fragments which underwent lysis (fig. 1). The degraded wall material captured by plasmalemma invaginations was then transferred to the central vacuole. It is suggested that in this way wall polysaccharides become mobilized allowing a partial survival of the cell population even after 4-day's carbon starvation. During the endocytic process the cytoplasmic islets are included into plasmalemmasomes; so these structures may be identified as auto-heterophagosomes (ambilysosomes by de Duve).
Ultrastructural aspects of gymnosperms reproductive organs tissues due to their functional condition
Authors: Kozubov G. M.
Published: June 2020

The ultrastructure of reproductive organs of pine, spruce, larch and ginkgo was investigated. It was found that the male reproductive organs possess similar organization. The most considerable change in the ultrastructure of the microsporocytes occur in meiosis. Sporoderm is being laid at the late tetrad stage. The cells of the male gameto-phyte are distinguished according to the metabolic activity of the or- ganells. They are most weakly developed in the spermiogenic cell. Ta-petum of the gymnosperms is of the periplasmodic - secretorial type. The Ubisch bodies which possess similar structure in the types investigated but are specific in details in different species are produced in tapetum.

Parietal and subepidermal layers are distinguished for their high metabolic activity and are capable of the autonomous photosynthesis. Female reproductive organs differ more greatly in their struture and have the most complicated structure in primitive groups. On the first stages of their formation the inner cells of nucellus are transformed into the nucellar tapetum in which the structures similar to the Ubisch bodies taking part in the formation of the sporoderm of female gametophyte have been found.
Ultrastructural morphometric investigations on human platelets
Authors: Themann H. , Stahl K. , Dame W.R.
Published: June 2020

Qualitative fine-structure examinations of human platelets have been carried out by a number of investigators (see for example WHITE (1972) and references in his report). It is the purpose of this report to characterize the normal values of morphometric variables occurring in human platelets.

Materials and Methods

Platelets were obtained from clinically healthy females with ages ranging from 18-32, all of whom had documented normal hematological findings (normal differential, platelet count, PT, PTT, and fibrinogen values) and no history of drug use for at least 2 months. All blood samples (one per donor) were obtained by large-bore (1.5 mm) needle puncture of the medial antecubital vein. Samples were treated in one of the following two ways:

(1)after disposal of the first ml, 9 ml were slowly drawn into a syringe containing 1 ml of 3.8% sodium citrate. Samples were then immediately centrifuged at 1000 x g for 1.5 min at 23°C.
Membranes and cytoskeleton in human platelets during webbing
Authors: Inczédy-Marcsek M. , Lindner E.
Published: June 2020

The intracellular membranes of blood platelets, dense tubular system (ER) and Golgi apparatus (GA), play a major role in platelet function. Their arrangement within spreading platelets as a model system is demonstrated by a modified osmium-ferro-cyanide postfixation method.

Venous blood was either dropped into the fixative, or citrated platelet rich plasma was dropped on carbon coated gold grids or plastic discs and incubated for 5 - 60 min in a moist chamber, 20° C.

Glutaraldehyde (GA) 0, 2-3, 5% or paraformaldehyde 4% in 0, 1 M-0, 15 M cacodylate buffer, pH 7, 4 (CACO) with or without glucose-dextran or 5 mM CaCl2 added.

1. 1% OsO4 in 0, 15 M CACO, 60 min, followed by 2% uranylacetate in H2O or 15% acetone, 10-60 min (Os-UA), 2. 0, 8% ferrocyanide in 2% OsO4 in 0, 12 M CACO, 2 hrs (Os-Fe).
Histochemical and autoradiographic findings on specific granules of the endothelial cells
Authors: Fujimoto Sunao , Yamamoto Koji , Takeshige Yoshio
Published: June 2020

Since the first description of specific granules of endothelial cells, similar electron dense granules have been described in various vessels. However, their chemical nature and function are still uncertain; the possibilities that they may be lysosomal bodies or peroxisomes have been completely denied by previous experiments.

A remarkable increase in number of endothelial specific granules was observed in the postnatal rabbit umbilical veins. The granules are very few in number in the prenatal vessels but many immatured forms of the granules have appeared near Golgi apparatus in the late fetal condition. The increase is the most pronounced between 2 and 10 days after birth, especially in the endothelial cells where the vascular lumen is obliterating (Fig. 1). The granules gradually decrease in number after 20 days and have almost disappeared at 30 days. The release of their content from the cell surface into the vascular lumen by exocytosis is supposed by our micrographs. Such transient increase at a particular condition of the vessels strongly suggests that these granules may have some function for the vascular obliteration.
The development of rat intestinal capillaries
Authors: Milici Anthony J.
Published: June 2020

Adult rat intestinal capillaries are characterized by the presence of extremely attenuated areas of endothelium penetrated by circular fenestrae which have a diameter of, 300-700 Å and are closed by thin diaphrams. This type of endothelium contains both pinocytotic (600-700 Å diameter) and coated (1000-2500 Å diameter) vesicles. Beneath this endothelium is a basal lamina which is 600 Å thick (Fig. #1). Electron dense tracers have been used by researchers to morphologically identify the above structures as belonging to the physiologically postulated two pore system in intestinal capillaries. No investigator to my knowledge has examined the development of fetal or neonatal intestinal capillaries. Such information may yield a better understanding of their function in the fetus and the adult. In this report, I describe the morphology of the developmental sequence of rat intestinal capillaries from the 14 day fetus through the 2 day neonate.
Pulmonary neuro-epithelial bodies—ultrastructure, surface morphology and effects of pharmaca in vitro
Authors: Cutz E. , Sonstegard K. S. , Chan W.
Published: June 2020

Recently, intraepithelial innervated corpuscles, referred to as neuro-epithelial bodies (NEB) have been identified within the airway mucosa of human and animal lungs. The specialized cells of NEB share certain features of APUD (Amine Precursor Uptake and Decarboxylation) endocrine cells, such as argyrophilia, amine contents and presence of cytoplasmic dense core vesicles (DCV). Although the precise function of NEB in lung remains still unknown, it has been suggested that NEB may represent intrapulmonary receptors or alternatively may have an endocrine function.

In this study, NEB in lungs of near-term rabbit fetuses (29 days gestation) were examined by transmission (TEM) and scanning electron microscopy (SEM), prior to and following short term organ culture. The ultrastructure and surface morphology of NEB in control animals was compared with a) NEB in rabbit fetal lung explants maintained in vitro for 7-10 days; b) lung explants incubated with reserpine, (an amine releasing agent) or Ca++ ionophore A-23186 (compound used for studies of calcium mediated secretion).
Morphological modifications of alveolar type II pneumocytes following cycloheximide treatment
Authors: Collet A. J.
Published: June 2020

Chemical, histochemical and radioautographic studies of surfactant have demonstrated that it is composed mainly of phospholipid (phosphatidylcholine) and of protein and polysaccharide material and that its production is closely related to type II pneumocyte (PNM). The question whether the components of surfactant are independently synthetized or are chemically bounded has not received a clear answer. Metabolic active substances have been used in vivo to observe the effects of protein inhibitors on the lamellar bodies formation and on the morphology of the type II PNM. In a previous study, puromycin has been used and a strong decrease of the lamellar bodies was observed; this decrease was dependent of the time interval after the administration, 125 and 155 min. respectively (Collet & Chevalier, 1974, 1977).

In the present study, cycloheximide, an other protein synthesis inhibitor, was utilized, which is known to act following a mechanism different of that of puromycin.
Inner surface ultrastructure of the lungs of frog and lizard
Authors: Bils R. F. , Hughes G. M.
Published: June 2020

Mammalian lung cells and tissues have been studied extensively, resulting in a voluminous literature. In comparison, the ultrastructure study of the respiratory systems of the lower vertebrates is incomplete. Lung surfactant and the related osmiophilic lamellar inclusions were observed in bird lung by Lambson and Cohn and in cultured frog lung cells by Soloff and Burns. This report compares the inner surface structure, cell types and vascularization in the lungs of frog and lizard.

Mature Rana pipiens and Lacerta viviparus lungs were fixed at normal volumes (approximately 0. 3 ml and 0. 05 ml, respectively) with cacodylate-buffered glutaraldehyde, post-fixed with OsO4 and processed for both TEM and SEM.

Frog Lung

Looking outward from the central duct, the septa divide the respiratory regions into smaller and smaller compartments, ending in closed sacs or alveoli, ranging from 150 to 300 mμ in diameter (Fig. 1). The largest or primary septa are covered by ciliated epithelium, whereas a squamous microvillous epithelium covers the minor septa and alveolar walls (Fig. 2). In section, the microvillous epithelial cells appear as a combination of type 1 and type 2 alveolar epithelial cells of the mammalian lung. Capillaries appeared as a random network through the septa and alveolar walls.
Application of electron microscopy to study of airborne fibres in work environments
Authors: Hwang C. Y. , Pidoux I.
Published: June 2020

Long term exposure to elevated levels of asbestos fibres has been recognised to cause asbestosis and to be associated with an increased risk of lung cancer. More recently, asbestos has been implicated as a factor in the occurrence of primary malignant mesothelial tumours of the pleura and peritoneum. In order to understand the relationship between the occupational exposure to asbestos fibres and prevelance of the asbestos-related diseases among the workers employed by the asbestos industry, it is necessary to examine size and shape of the respirable fibres present in the work environments. While fibrils found in a worker's lung at autopsy have been as small as 0. 01μm in diameter, fibres as long as 200μm are sometimes found in the lung. Electron microscopy thus becomes essential for the study of size and shape of asbestos fibres in view of wide range of fibre size.
An ultrastructural study of the alveo-capillary block of the lung induced by E. Coli endotoxin—a correlative cytochemical and biophysical study
Authors: Yokoi Kimiyoshi , Sasamoto Yoshinobu , Shirota Deog Young KIM Akiro , Aihara Kaoru , Yajima Gompachi
Published: June 2020

The Endotoxin(E. Coli 0-26) has been regarded as the most frequent and outstanding causative factor of the shock in the lung. More importantly the substance is acting as the casuative factor of the clinically observed disseminated intra-vascular coagulopathy. In this connection the substance may play a very important roll in causing the alveo-capillary block. A rather extensive survey of the biophysical, morphological investigation has been undertaken and the present communication is dealt with the rather earlier changes of the blood-air barrierr which eventually leads to the alveo-capillary block. Incidentally a correlative study with the alteration of the alveolar lining layer which may possess the interface action(Pulmonary surfactant) and qualitative determination of the interface action.

The adult rats of both sexes served as materials. They recieved repeated injections of E. Coli endotoxin 0-26, l00mg/kg. and sacrified by decapituation chronologically.
A scanning electron microscopic study of human cholesterol gallstones
Authors: Funatsu K. , Oda M. , Edwards V. , Chan Joyce , Phillips M. J.
Published: June 2020

Structural studies on cholesterol gallstones have been the subject of relatively little investigation despite the fact that a number of authors have shown that the scanning electron microscope (SEM) can provide excellent visualization of their surface and internal structure. It is recognized that there are many types of gallstones but cholesterol is their main constituent in North America. Since major efforts are now being made clinically to dissolve cholesterol stones in vivo using bile acids and other agents, it was deemed useful to study by SEM the common multifacetted gallbladder stone since it is likely that the structure of such stones influence their dissolution. Multifacetted cholesterol gallstones obtained from human gallbladders were prepared for SEM using standard techniques. Stones were divided equally into two halves, one of which was mounted with its outer surface up, the other with its cut surface up, on an aluminum stud by means of conductive paint.
Epithelial cell basal processes in the duodenum of NZB mice
Authors: Partridge B. T. , Simpson L. O.
Published: June 2020

Although spontaneous peptic ulcers in NZB mice were described first in 1965 and the incidence of the lesion reported two years later no studies of the fine structure of the lesions have been reported. During the course of a scanning electron microscope study of the proximal duodenum of NZB and related mouse strains focal lesions previously unreported were observed. Early lesions were characterised by loss of epithelial cells from the tips of villi. Recently denuded basement membrane had a very rough surface and it was noted that pores 0. 5 to 1. 0 microns in diameter, (Fig. 1) were arranged in rows with regular interspaces between the pores. Epithelial cells which had fallen from the villi in sheets revealing their basement membrane aspect had elongated basal processes (Fig. 2, 3). In a study on the morphology of the human small intestine (Trier, 1968) it was noted that, “Occasionally small pseudopod-like extensions of cytoplasm may penetrate the basement membrane and project into the lamina propria from the basal surface of intestinal epithelial cells”.
Immuno and histochemical electron microscopic studies of the selective permeability, involving the feto-maternal junctional barrier
Authors: Hata Toshio , Ohkawa Kimiyasu
Published: June 2020

Regarding to the cellular transfer and absorption mechanism of the trophoblast in the feto-maternal junctional zone, it is awaited futher confirmation in the future. Numerous documentation has been accumulated on this aspect, utilizing the visible markers such as the fat(Yamaguchi), ferritin(Tillack) and IgG(Morphis). however, the observations are mainly based on the investigations of the placenta in vitro. From this view point, the authors have made a rather comprehensive observation of the cellular transfer and absorption mechanism of the human feto-maternal junction in physiological circumstance.

Materials and methods: The specimens of the human uterus in early ges tation are removed surgically for therapeutic purpose had served as materials. The chorionic tissue and implanted tissue from the uterus were carefully investigated. The method of the investigation are as follows: 1) Conventional transmission electron microscopic observation with double electron stains. 2) Visualization of the iron dextran(Fesin), it is usually used to iron deficiency anemia, which was administered prior to the surgical removal of the uterus.
Paracrystalline structures in the oocytes of a mouse, mus cervicolor poppaeus
Authors: Szöllösi Daniel , Claussen Claus-Peter
Published: June 2020

Large and multiple paracrystalline bodies exist in the cytoplasm of the oocytes of a wild mouse strain originating in Thailand, Mus cervicolor poppaeus. The structural details of these crystals are identical to much smaller paracrystalline structures described in preimplantation embryos of the laboratory mouse, Mus musculus (Enders and Schlafke, 1965; Calarco and Brown, 1969; Calarco and Szöllösi, 1973). These latter often occur in close proximity or even in contact with the rough endoplasmic reticulum (RER). A number of A-type virus like particles bud into these cirternae. In spite of the fact that thus far no intracisternal A-type particles were recognized in oocytes of Mus cervicolor poppaeus the similarity between the two paracrystalline structures warrants their description and comparison.

In the cytoplasm of oocytes we collected by puncture from large Graafian follicles of Mus cervicolor poppaeus. In one micron sections stained with Richardson´s strain (Richardson et al., 1960), rhomboidal crystalline bodies of various sizes can be recognized. The crystalloids stain intensely blue (Fig. 1).
Ultrastructure of the decidual cells of the basal plate of the human placenta at term
Authors: OliVar C. , Castejon S.
Published: June 2020

To understand the role of the decidual cells of the basal plate of the human placenta at term in the passage of the antigens and antibodies, in the production of hormones, in the nutrition of the embryo and its possible function in the formation of fibrilar proteins, a systematic study of their ultrastructure has been necessary.

Immediately following a spontaneous delivery, samples of the decidua were taken and fixed by immersion in 2% g1utara1dehyde in phosphate buffer 0. 2 M (PH 7. 4). The specimens were washed in a similar buffer for 1 hour and postfixed in 2% osmic acid in phosphate buffer 0. 2 for 3 hours at 4°C. After dehydrating the samples in a graded series of ethanols and propylene oxide they were embedded in Araldite. Ultrathin sections were then stained with uranyl acetate and lead tricitrate and examined under the electron microscope. The submicroscopic observations show that: The plasmamembrane of these cells demonstrates numerous irregular, globulous or polyhedral extensions (Fig. 1a), which intermix with the intercellular substance or connect with adjacent cells by means of desmosomes (Fig. 1b). The hyaloplasmic matrix (Fig. 2) is of low electron density, homogenous, with numerous free ribosomes and cytoplasmic microfilaments (Fig. 4) which are arranged in bundles dispersed throughout the cytoplasm in different directions.
Sperm binding and formation of the fertilization envelope by surface complexes isolated from sea urchin eggs
Authors: Decker Glenn L.
Published: June 2020

During fertilization of the echinoderm egg the sperm cell undergoes the acrosomal reaction and binds species-specifically to the vitelline layer, which is attached to the exterior surface of the egg plasma membrane. Following initial interaction and fusion of the limiting membranes of the egg and the sperm, the cortical vesicles attached to the inner surface of the egg plasma membrane (Fig. 1) fuse and secrete components which appear to modify the vitelline layer, giving rise to the fertilization envelope.

Recently, the surface and associated secretory vesicles of the egg were isolated from homogenates by differential centrifugation in sea water containing 25 mM EGTA (Fig. 2) (2). Determination of the extent to which this cell surface-secretory complex can be induced to mimic fertilization related events observed with intact eggs is currently in progress.
Some observations of the morphology of the glial and neuronal cell populations in monolayer culture
Authors: Wong Y. C. , Garber B. B.
Published: June 2020

Attempts have been made in the past to separate the glial and neuronal populations of cells for various studies. The homogeneity of cell populations achieved using these methods remains to be improved. Using a modified separation method and combined with subculturing, very pure glialand neuronal populations have been obtained. This paper reports the surface features and some properties of the two cell populations using the modified culture method.

Ten day old chick embryo cerebra were removed aseptically and the meninges carefully excised. The tissues were washed in calcium and magnesium free (CMF) tyrode solution before incubation for 35 min. at 37°C in 0. 2% of trypsin in CMF. The cells were dissociated in E-II medium by gentle flushing of the tissues with a fine bore pipette for about 20 times. To each of the 35 mm culture dishes containing 2 ml of E-II medium and a poly-L-lysine coated coverslip, one ml of cerebral cell suspension was added and the cells were allowed to plate on a coverslip for 7 minutes at room temperature.
Morphological and morphometric studies of epidermal merkel cells and associated nerve endings
Authors: Kurosumi Kazumasa
Published: June 2020

The Merkel cell is the only cell type of the epidermis that is known to be sensory in nature, because it is always associated with a nerve fiber in normal skin. This cell type is more easily found by electron microscopy rather than light microscopy, as it contains characteristic granules. The chemical composition of these granules has not been known, but they seem to be closely related to the function of this cell, because the granules tend to be accumulated in the cytoplasmic area near the adjoining nerve terminal. Therefore, counting the number of these granules is available for determining the functional state of this cell. Morphometric examinations on the population and distribution of these granules especially after denervation were performed along with a simple morphological observation of the ultrastructure of this cell.
Quantitation of calcium in native myocardial and fractioned sarco-plasmic reticulum by electron probe X-ray microanalysis
Authors: Wendt-Gallitelli M. F. , Schlote W. , Wolburg H. , Schwegler M.
Published: June 2020

The importance of the sarcoplasmic reticulum in the regulation of myocardial contraction is today still unclear. X-ray microanalysis of elements in the cell compartments involved in excitation-contraction coupling can contribute to the understanding of this question if the following prerequisites are met: treatment of the tissue should not alter the distribution of diffusible ions, and the method of detection should be sufficiently sensitive.

In order to test whether electron probe microanalysis is suitable for myocardial Ca in sarcoplasmic reticulum, ultrathin cryosections were taken from native myocardial tissue and from isolated sarcoplasmic reticulum of the cat. This fragmented sarcoplasmic reticulum (FSR) was chosen for two reasons: first, if the x-ray microanalysis of isolated active SR vesicles maximally loaded with Ca did not show Ca, further experiments on myocardial tissue using this method would have been useless. Second, if Ca identification is possible using this method, the isolated FSR can be utilized as a standard for quantitation of Ca in native tissue since the amount of Ca taken up in the FSR is known before the analysis and can be arbitrarily varied.
SLS crystallites and reconstituted fibrils made from locust collagen
Authors: Ashhurst Doreen E.
Published: June 2020

That insects possess collagen fibrils similar to those of vertebrates is well established. In some insects, the fibrils are very thin and indistinctly banded, while in others, for example, locusts and cockroaches, fibrils of larger diameter and distinct banding are found. Estimates of the periodicity of the banding of sectioned fibrils range from 56nm to 63nm (see 2), but the interband patterns are similar; the variation in the periodicity is probably due to the preparative procedures. A peculiarity of many of the fibrils is that on ageing they become very large and irregular in cross-section; typical examples are found in the connective tissue around the ejaculatory duct of 2-3 week old adult male locusts, Locusta migratoria. Similar large, irregular fibrils are found in some pathological conditions in mammals. One way to establish similarities between collagens is to compare their segment-long-spacing (SLS) crystallites and reconstituted fibrils, and so these experiments were performed with locust collagen.

Locust collagen is not readily soluble in salt or dilute acids, and so to increase its solubility, newly-moulted, adult male locusts were fed on wheat seedlings sprayed with a 1% solution of β-aminoproprionitrile, a lathrytic agent which reduces cross-linking in mammalian collagens.
Artifacts on the surface of articular cartilage due to drying methods
Authors: Hesse I. , Hesse W.
Published: June 2020

Since the advent of scanning electron microscopy very contrasting studies on the surface topography of normal and pathological cartilage have been published. The existing literature did not respect the influence of tissue preparation, especially the effect of the drying techniques. Thus the results lead to wrong conclusions. The purpose of this paper is to compare the preservation of the surface morphology obtained from three drying techniques, i. e. air-, freeze- and critical-point drying.

Our experiments were performed on normal articular cartilage of 50 sheep, on transplanted cartilage of 45 sheep and on articular cartilage taken intraoperatively from 33 patients. Three adequate samples of articular cartilage attached to bone were dissected out of the weightbearing portion of the medial femoral condyle for air-, freeze- and critical-point drying. They were rinsed in 4 changes of cacodylate buffer (pH=7. 2-7. 4).