bluuebunny/crossref_metadata_2025 huggingface dataset:
Fine structural, cytochemical, and phagocytosis studies of sinusoidal cells (SLC) of the mouse liver
Authors: Stöhr G. , Fahimi H. D.
Published: June 2020

The mononuclear phagocytes of the rat liver (Kupffer cells) contain an endogenous peroxidase in the endoplasmic reticulum (ER) and nuclear envelope (NE). Phagocytosis studies have revealed that large latex particles (0. 8)μm) are exclusively phagocytized by such peroxidase positive cells. In view of known species differences in localization of peroxidase in mononuclear phagocytes, and since most immunological studies are performed in mice, we have investigated the localization of endogenous peroxidase in SLC of the mouse liver.

Livers of male and female Swiss albino mice weighing 25-35 g were fixed by perfusion through the portal vein for 5 min. using 1. 0-5. 0% purified glutaraldehyde buffered with Na-cacodylate, pH 7. 2. Two min. prior to fixation some animals were given an intravenous'injection of 0. 8 μm latex particles (0. 05 ml/100 g). Fifty micron chopper sections were incubated for localization of endogenous peroxidase, followed by processing for electron microscopy.
Incidence of non-specific esterase during cleavage of rat ovum
Authors: Trávník Pavel
Published: June 2020

For the study of non-specific esterase on electron microscopic level the method with incubation medium described by Hanker et al. (1972) and modified by Trávník (1977) was used. The object of the study was the 1-,2-,4-,8-cell rat ovum, early and late blastocyst. To differentiate organophosphate sensitive and organophosphate resistant esterases, inhibition by means of diethyl-p-nitrophenyl phosphate (E 600) was used in the concentration of 10μ mol/1. As substrates thionaphthylacetate (TNA) at pH 7 and thioacetoxybenzanilide (TAB) at pH 5.6 were used.

Distinct activity of organophosphate sensitive esterase has been proved in aggregations of vesicles and tubules of smooth endoplasmic reticulum (Fig. 1). In the course of cleavage the total organophosphate sensitive activity is reduced together with the decrease in the amount of the smooth endoplasmic reticulum. In our opinion the aggregations of vesicles of smooth endoplasmic reticulum represent the site of reserve of hydrolytic enzymes synthetized during oogenesis, as a similar trend has been observed also in acid and alkaline phosphatases (astná 1977, 1978).
Three dimensional analysis of the eggshell fromDrosophila melanogaster
Authors: Margaritis Lukas H. , Kafatos Fotis C.
Published: June 2020

Formation of the insect eggshell is being studied as a model case of cell differentiation. Because of the potential for genetic analysis, we are concentrating on the eggshell ofDrosophila melanogaster. Here we summarize our understanding of the wild type structure as determined using a variety of ultrastructural methods. Follicles, eggshells or pure endochorion were prepared as described and studied with a Philips 301 TEM, an AMR 1000 SEM, a JSM-35 SEM, and a JEM-1000 high voltage electron microscope. Glutaraldehyde fixation (Figs. 6, 8, 9) followed by OsO4, (Figs. 1, 3, 4, 7, 10, 11) was used.

Thin sections (Fig. 1) of stage 14 follicles reveal the following layers of the mature eggshell from the oocyte surface outwards: vitelline membrane (VM), intermediate chorionic layer (ICL), endochorion (END) and exochorion(EX). The amorphous VM and the loosely fibrous EX appear simple in structure. The ICL has been purified and shown by negative staining to have a prominent crystalline structure (Fig. 2) which has been further investigated by optical diffraction and filtering.
Neuron-glia relationship during the early postembryonic development of the nervous system in some oligochaetes
Authors: Djaczenko Wiktor , Calenda Cimmino Carmen
Published: June 2020

The simplicity of the developing nervous system of oligochaetes makes of it an excellent model for the study of the relationships between glia and neurons. In the present communication we describe the relationships between glia and neurons in the early periods of post-embryonic development in some species of oligochaetes.

Tubifex tubifex (Mull. ) and Octolasium complanatum (Dugès) specimens starting from 0. 3 mm of body length were collected from laboratory cultures divided into three groups each group fixed separately by one of the following methods: (a) 4% glutaraldehyde and 1% acrolein fixation followed by osmium tetroxide, (b) TAPO technique, (c) ruthenium red method.

Our observations concern the early period of the postembryonic development of the nervous system in oligochaetes. During this period neurons occupy fixed positions in the body the only observable change being the increase in volume of their perikaryons. Perikaryons of glial cells were located at some distance from neurons. Long cytoplasmic processes of glial cells tended to approach the neurons. The superimposed contours of glial cell processes designed from electron micrographs, taken at the same magnification, typical for five successive growth stages of the nervous system of Octolasium complanatum are shown in Fig. 1. Neuron is designed symbolically to facilitate the understanding of the kinetics of the growth process.
Cell junctions in the compound eye of the worker honey bee
Authors: Nickel E. , Scheck G.
Published: June 2020

The ommatidium of the compound eye of the honey bee consists of visual or retinula cells which form a fused rhabdom. Each ommatidium contains three types of receptors which are sensitive to u. v., blue or green light. The ommatidium is isolated from its neighbours by secondary pigment cells.

Electrical recordings from single retinula cells have shown sensitivity curves with double peaks. Basicly these two peaks can arise from two different photopigments in one receptor cell or from electrical coupling between two receptor cells of different spectral sensitivity.

The present electron microscopic study was carried out in order to search for Junctional specializations between different cells in the ommatidium of the worker bee. These junctions are of particular functional interest because of their role in restricting extracellular fluid movement as well as in electrical coupling between cells. In freeze-cleaved specimens intercellular junctions can be identified on the characteristic array and size of intramembranous particles.
A scanning electron microscope technique for identifying myelinated axons
Authors: Friedman Peter
Published: June 2020

A technique is presented here which facilitates the identification of myelinated axons in human spinal nerves and spinal cord using the scanning electron microscope (SEM). By examining the backscattered electron (BSE) image of a modified osmium-thiocarbohydrazide-osmium (OTO) treatment the myelin sheaths of individual axons can be identified.

Two factors contribute to this BSE imaging: 1) multiple layers of osmium (mediated by the osmiophilic ligand thiocarbohydrazide, NH2NHCSNHNH2) are deposited in the tissue during the 0T0 treatment, and 2) since the myelin sheath contains the greatest concentration of unsaturated lipids, it incorporates more osmium than any other neural structure. This enhanced mass-density of the myelin sheath will then be imaged in the BSE mode of the SEM as a brighter area due to the greater number of primary electrons being backscattered by the osmium.
Electron microscope study on the glial filaments of astrocytes in the rat brain
Authors: Mori S. , Furukawa K. , Abe H.
Published: June 2020

With the electron microscope, it was demonstrated that the glial filaments existed in astrocytes and could be impregnated by Cajal's gold chloride sublimate solution. By this conspicuous structure of glial filaments, thus, the astrocytes have long been differentiated from other glial cells from the classical light microscopic studies till the recent electron microscopic observations. Further investigations could add the new knowledge on this important component of glial cells in this laboratory that the actin- like filaments might be contained among the glial filaments. It will be shown in this report that glial filaments of astrocytes are consisted of the heterogenous groups of filaments, and some of them can bind with the heavy meromyosins (HMM).

Normal rats (about 120 g body weight) were anesthetized with Nembutal and fixed by perfusion through the heart for 30 minutes with the fixative. This fluid was consisted of 3 % glutaraldehyde, 2 % paraformaldehyde, 4 % sucrose and 0. 5 mM CaCl2 in 0. 1 M phosphate buffer at PH 7. 4.
Ultrastructural studies of pigmented, depigmented and melanomatous skin in lipizzaner horses.
Authors: Gebhart W. , Niebauer G.
Published: June 2020

Lipizzaner horses - as well as some other graying breeds - undergo progressive depigmentation of their coat color and are regularily affected by melanotic tumors at older age. Although deeply pigmented at birth nearly all individuals loose their dark color at the age of 4 — 6 years and multiple melanotic tumors arise in skin. Unique melanomatosis is frequently present in 20 — 30 years old animal (Gebhart and Niebauer, 1977). These characteristics design the horses of the genetically well-defined Lipizzaner breed as a suitable animal model for studies on depigmentation and tumor formation processes. Histochemical and ultrastructural investigations were performed in order to elucidate the morphological substrates of pigmented and depigmented lesions.

Biopsy specimens were obtained by surgical excision from pigmented and depigmented skin and from melanomas of 19 Lipizzaner horses. Immediately after excision the tissue was devided into several portions and processed for routine histology, DOPA-reaction and electron microscopy. Ultrastructural investigations were performed in a ZEISS EM 9S2 and a JEOL lOO C TEMSCAN electron microscope fitted with a computer based energy-dispersive spectrometer (LINK).
The tendon — a homeostatic unit tuned to mechanical forces
Authors: Merrilees M. J. , Gillard G. C. , Flint M. H.
Published: June 2020

To determine the role of mechanical forces in the maintenance and control of cell and matrix organization of connective tissues, we have undertaken a morphological and biochemical study of the rabbit hind limb Flexor Digitorum Profundus (FDP), a single tissue which is subjected to both tensional and compressive forces during normal function. Like all tendons, the FDP is designed to transmit tensional forces, but as it passes below the ankle a segment in contact with the calcaneum and talus is subjected to additional compressive forces. In this region the anterior half of the tendon is thickened to form a lenticular shaped sesamoid-type pad (Fig. 1) where cell and matrix organization resembles fibro-cartilage.

The tensional regions of the FDP are characterized by elongated, flanged fibroblastictype cells intimately surrounded by densely packed, positively charged, collagen fibrils of long periodicity (63 nm) (Figs. 2 & 3), and small amounts of proteoglycan (0. 15% dry wt. ), predominantly dermatan sulphate.
Microanalysis in mitochondrial granules of bone cells incident to experimental tooth movement
Authors: Hirashita A. , Nakamura Y. , Okumura E. , Kuwabara Y.
Published: June 2020

Biological functions of Ca in mitochondrial granules have been reported by a number of investigators. It is said that mitochondrial granules of chondrocytes, osteoblasts and osteocytes in rat epiphyseal growth plate with regard to bone calcification and these granules of osteoclasts at bone-resorbing site play an important role of Ca-transport. However, these results were reported about the first stage of calcification in rat epiphyseal growth plate, so that the changes of bone tissues in adult rats seem to be not always the same.

The purpose of this work is, by electron probe X-ray microanalysis method, to do the elemental analysis in mitochondrial granules of osteoblasts, osteocytes and osteoclasts incident to experimental tooth movement in adult rats, and to compare them with these analysis in control groups.
Energy dispersive microprobe analysis of intracellular mineral deposits in rat bone
Authors: Dempster D.W. , Nicholson W.A.P. , Elder H.Y. , Smith D.A.S. , Ferrier R.P.
Published: June 2020

The use of an energy dispersive X-ray microanalytical system (EDX) attached to a conventional transmission electron microscope (TEM) allows images of good morphological resolution from ultra-thin specimens and spectra of all detectable elements to be obtained simultaneously at radiation doses which are low compared to wavelength dispersive detectors. For reasons of detection efficiency the solid angle subtended from the specimen to the detector is maximised (∼0.l sterad) in our system, a LINK SYSTEMS 290 with a 30mm2Si(Li) crystal fitted to a JEOL JEM lOOC. However, with this type of system the recorded spectrum has contributions not only from the small areas which can be probed but also from scattered electrons, and X-rays originating in the surrounding specimen, the specimen support system and the microscope environment of the specimen. The problem is particularly acute in projects, such as the present, where it is necessary to detect and determine the ratios of elements (Ca and P) in small quantities in close proximity to relatively massive concentrations of the same elements.

Modifications to our system have been described (Nicholson et al., 1977a;Biddlecombe et al., 1977) which greatly improve the peak/background ratios for quantitative analysis and eliminate all of the specific peaks of non-specimen origin. For ease of maintenance the JEOL 100C is fitted with thin foil condenser apertures (10μm thick molybdenum) as standard. At the accelerating voltage used in this study (80 keV) a considerable number of electrons are transmitted by these apertures and with the electron probe placed adjacent to fully mineralized bone the scattered electrons were responsible for generation of sizeable Ca and P signals. We have replaced the standard foils with thick (0.25 mm) molybdenum apertures.
Ultrastructural studies of cartilage in genetic disorders of skeletal growth
Authors: Sillence D. O. , Rimoin D. L. , Silberberg Ruth
Published: June 2020

The human skeletal dysplasias are an heterogeneous group of heritable connective tissue disorders associated with abnormalities in the size and shape of the limbs, trunk and/or skull which frequently result in disproportionate short stature. In recent years it has become apparent that these comprise over 50 distinct conditions with a variety of subtypes distinguished on clinical and radiological grounds. We have investigated the pathogenesis of these conditions in over 100 patients by direct transmission electron microscopic examination of chondro-osseous tissue. Some of the ultrastructural studies have been previously reported.

Small biopsies of chondro-osseous junction were collected for electron microscopy from the rib or iliac crest of patients with skeletal dysplasias or from normal controls at the time of surgery. These were cut into small blocks and fixed for one hour in either 5% glutaraldehyde in white's buffer or directly in 1% osmic acid in White's buffer or a modified Karnovsky's fixative, (2. 5% paraformaldehyde, 2. 5% glutaraldehyde, 2. 5mM calcium in cacodylate buffer). Subsequent processing included osmium fixation, block staining with uranyl acetate and embedding in Araldite or Spurr's low viscosity resin (firm composition). Sections were cut with glass knives or diamond knives. The latter produced sections which were much more even in thickness, permitting more consistent appraisal of matrix features.
Bone tissue response to dense hydroxylapatite disc implants in mongrel dogs: a light and electron microscopic study
Authors: Jasty V. , Jarcho M. , Gumaer K. I. , Sauerschell R. , Drobeck H. P.
Published: June 2020

Ceramics have distinct advantages over many other materials for use as implantable prosthetic devices. As implant materials, they are virtually nonreactive, and unlike many metals they are corrosion resistant. When properly formulated and fabricated, their compressive and tensile strengths would be appropriate for use as prosthetic devices. A new process for preparing a dense polycrystalline hydroxylapatite (HA) ceramic called durapatite has been formulated. This material appears particularly attractive as a candidate for hard tissue implant because of its strength and because its chemical composition closely resembles that of vertebrate bone and tooth minerals.

Durapatite in the form of dense plugs was surgically implanted into drilled holes in the femurs of four adult mongrel dogs. Two dogs were sacrificed two months postimplantation and two at approximately seven months.
Evaluation of the interface between calcified bone and metal implants
Authors: Krizan K. E. , Han D. H. , Ettinger R. L. , Koorbusch G. F. , Spivey J. D.
Published: June 2020

In recent years oral endosteal implants have been placed in healed extraction sites but it has been suggested that osseointegration may not occur. This study places IMZ implants1 in fresh extraction sites with and without two biological graft materials: porous hydroxyapatite granules (HA) and polytetrafluorethylene (PTFE) membranes. The purpose of this study was to investigate the influence of immediate placement of implants on osseointegration. This presentation uses the scanning electron microscope (SEM) to evaluate the relationship of implant to bone. In addition, the effect of these two graft materials on bone regeneration and prevention of soft tissue (ST) ingrowth was examined. Under anesthesia three adult mongrel dogs had premolars extracted bilaterally from the mandible. Using the IMZ system six implant sites were prepared, five implants placed in alveolar bone and the sixth site was a no implant control. A total of fifteen implants were placed in the area between the canine and first molar of the three animals.
Comparative ultrastructure of conventionally fixed and high-pressure frozen chloroplasts of Vitis vinifera
Authors: Sadowski Laura A. , Bricker Connie S. , Keegan John F.
Published: June 2020

Chemical fixation of biological samples for transmission electron microscopy is still the most widely used method because of the availability of low cost chemicals and universal knowledge of the fixation protocol. Microscopists are very familiar with images of the chemically fixed cell with its irregular membranes, flattened Golgi cisternae, elongated mitochondria and football-shaped chloroplasts. But the advent of high quality ultra-rapid freezing techniques in the past decade or so has greatly increased our knowledge of cellular ultrastructure and altered our perception of biological material preserved in a “lifelike” state. While many of the best freezing techniques achieve a depth of well frozen tissue to only 10-40μm, the high pressure freezing method (HPM) yields well preserved tissue samples to approximately 600μm. Although the HPM is becoming more popular, it is still a relatively novel technique.
High-pressure freezing and freeze-fracture replication of starch gels for high-resolution TEM
Authors: Basgall E. J. , Day G. A.
Published: June 2020

Gelled food products with a high water content (∼80%) must be vacuum stabilized for electron microscopic studies of their ultrastructure. Conventional chemical fixation techniques produce unacceptable artifacts when applied to many gel or emulsion type samples. Rapid freezing is necessary in order to stabilize the matrix without appreciable ice crystal formation. High pressure freezing has been shown to produce vitrification of thick samples (up to .5 mm).

Freeze-fracture/etch surface replication and TEM has been used successfully to visualize the spatial structure of aqueous carboxymethyl cellulose gels after ultra rapid freezing/Cryo-SEM has, been used to study starch gel and food emulsion structure directly. Cryo-SEM is generally limited in resolution and does not provide structural details in the 10-20 angstrom range. High pressure freezing and freeze-fracture replication is the preferred method for immobilizing and studying ultrastructural details at high resolution.
Ice damage resulting from crystallization of bound water in freeze-dried cells
Authors: Wray G. P. , Grant K. W. , Lewis J. C.
Published: June 2020

Rapid freezing followed by freeze-drying is widely used as a strategy to preserve the 3-dimensional architecture of cells and tissues. This combination of methodologies is proving invaluable as a complementary approach to chemical fixation and critical point drying in studies which are concerned with subtle arrangements of the cytoplasmic matrix. As with other preparative techniques, freeze-drying raises questions, one of which is the degree of dehydration obtained during the drying process. We present data here that under conditions typically used for freeze-drying, sublimation of cell water is incomplete, and this residual water alters cytoarchitecture during the post-dry warming phase.

Human blood platelets, obtained from healthy donors following informed consent, were separated from anticoagulated (1 part 3.8% sodium citrate to 9 parts blood) blood and washed in balanced salts to remove plasma proteins. The cells were then adhered for 30 minutes at 37°C to carbon-stabilized formvar-coated, gold grids, and then rapidly frozen with a modified Gentleman Jim apparatus by plunging into liquid N2 cooled propane. The frozen cells were then transferred to a custom built freeze-drying module which was mounted on a Denton DV-502 vacuum system.
Electron Microscopic observations of channel catfish macrophages infected with Edwardsiella ictaluri
Authors: Stanley L. A.
Published: June 2020

Edwardsiella ictaluri, a gram negative rod shaped enteric bacterium, is the etiological agent of Enteric Septicemia of Catfish (ESC). Little is known about the pathogenic mechanisms operative in ESC. It has been reported that infected macrophages are apparently unable to destroy the bacterium. The objective of this study was to detect differences in the way E. ictaluri virulent and avirulent strains associate with and are engulfed by channel catfish macrophages. This should help to characterize the possible role macrophages play in the disease process of ESC.

The virulent bacterial strains used in this study were isolated from the kidneys of moribund channel catfish. Attenuated avirulent forms were derived from virulent strains by subsequent passages on Brain Heart Infusion Agar. The virulent and avirulent types were metabolically identical. Channel catfish, Ictalurus punctatus, were used as the susceptible host animals for experiments. For phagocytic studies, channel catfish macrophage suspensions were prepared as described by Trust et al.
High-voltage electron microscopic studies of the interrelationship between microglial cells and amyloid fibrils in scrapie-infected mouse brains
Authors: Lossinsky A. S. , Song M. J. , Wisniewski H. M.
Published: June 2020

We have previously demonstrated the usefulness of high-voltage electron microscopy (HVEM) in the study of microvessels and inflammatory cell attachment in the central nervous system (CNS). In the present study, we used HVEM to further explore the interrelationship between microglial cells (MCs) and amyloid deposits in scrapie-infected mice. Scrapie infection in the mouse has been employed as an animal model to study the pathogenesis of amyloid fibril formation. The central question was whether three-dimensional (3-D) stereo-pair reconstruction would offer further insight into amyloid formation by MCs, which is currently the view of our group. Brains or cervical spinal cords from IM mice previously inoculated with 87V scrapie agent were used. One-half-micrometer thick plastic sections were stained with uranyl acetate and lead citrate. Light-microscopy views enabled us to target primary inoculation channels associated with amyloid deposits. Cells located at the periphery of the amyloid were identified as MCs (Fig. 1).
Early atherogenic events in the proximal aorta of the hyperlipidemic New Zealand white rabbit
Authors: Klemp K.F. , Guyton J.R.
Published: June 2020

The earliest recognized atherogenic event in the cholesterol-fed New Zealand White Rabbit is the accumulation of extracellular lipid in the subendothelial space. This event, which was reported to precede foam cell formation, is probably the result of transcytosis by the endothelium ofβ-VLDL particles which circulate in excess in the blood due to hyperlipidemia. The extracellular lipid was described as being uni or multilamellar vesicles consisting of phospholipid and unesterified cholesterol,β-VLDL particles, however, contain cholesteryl ester as their major lipid constituent and the presence of this neutral lipid was not demonstrated due to its extraction by dehydrating solvents. A lipid cytochemical technique that allows visualization of both vesicular and neutral lipid was developed in our laboratory and was employed to study this early lipid deposition.
The prompt demonstration without culturing of gram-negative bacteria in burn wound infections
Authors: Hanker J.S. , Giarnmara B.L. , Hopfer R.L. , Peterson H.D.
Published: June 2020

Burn wound sepsis is the most important factor in the morbidity and mortality associated with major burns. Blood cultures often give false negative results and wound biopsy is a much more accurate and reliable means of assessing the burn's microbial status. From 1950 to 1965, due to the introduction of antibiotics, gram-negative organisms became predominant among those recovered from burn wound infections. Although few grampositive organisms are now seen in Gram-stained burn wound biopsies, the light pink or red staining of gram-negative organisms can occasionally go unnoticed (Fig. 1). This is not the case when the biopsy sections are stained with the new positive PATS stain developed in our laboratories for gram-negative bacteria. This reaction deposits silver on the lipopolysaccharides of the outer walls of gram-negative, but not gram-positive, bacteria. The assessment of the microbial content of the specimen site as colonized, infected, or having mixed or unmixed gram-negative microbes is facilitated by this stain (Figs. 2-4).
Changes in peroxisome number and volume after exposure to various mixtures of polyCTFE
Authors: Mattie D.R. , Chase M.R. , Maslanka J.J. , Grabau J.H. , DelRaso N.J.
Published: June 2020

Polychlorotrifluoroethylene (POLYCTFE) is a candidate base stock for a nonflammable hydraulic fluid under consideration for advanced aircraft and ground systems. PolyCTFE consists of oligomers with 3 and 4 units, trimer and tetramer, blended to achieve a viscosity of 3.1 (3.1 oil). Although acutely nontoxic, repeated inhalation exposure of rats to the 3.1 oil resulted in hepatocytomegaly with an increased number of peroxisomes identified by counts made on photomicrographs. A comparative study was conducted to evaluate the relative toxicity of the different oligomers and two formulations of 3.1 oil. In rats pure tetramer was toxic while pure trimer had little toxicity. The standard 3.1 oil formulation of PolyCTFE (C6:C8 oil), consisting of trimer and tetramer in a ratio of 55:45, produced toxicity similar to the pure tetramer. The 3.1 oil formulation of PolyCTFE, consisting of trimer and high molecular weight oligomers in the C10 range with a ratio of 95:5 (C6 oil), produced toxicity similar to pure trimer. The objective of this study was to quantitate by number and volume peroxisomes in hepatocytes from the comparative study.
ESI detection of titanium in lungs of a spray paint sniffer
Authors: Tryka A. F. , Cox W. E. , Van Devanter S. H.
Published: June 2020

Do lungs of inhalation substance abusers contain materials indicative of such abuse, and is it possible to detect these materials by electron energy loss spectroscopy? While most abuse involves only volatile materials, spray paint is one material where when volatile materials evaporate, resultant solid particles may be of respirable size. These particles may contain paint pigments such as titanium dioxide.

Lung biopsy tissue was obtained for diagnostic purposes from a 16 year old male who presented with acute onset of progressive respiratory insufficiency. The patient later admitted to a history of significant paint sniffing. Desquamative interstitial pneumonitis was observed by light microscopy, with an unusual additional feature of many alveolar macrophages having dusty cytoplasm. Routine ultrastructural study demonstrated large amounts of electron dense material in these macrophages. To address the question of what materials were present in the cells, additional tissue samples were embedded in Araldite, sectioned at 30 nm, and viewed unstained on a Zeiss 902.
Ultrastructure of the effect of T-514 obtained from Karwinskia humboldtiana on assembly and integrity of yeast's peroxisomes
Authors: Sepulveda-Saavedra J. , Vander-Klei I. , Venhuis M. , Piñeyro-Lopez Y.
Published: June 2020

Karwinskia humboldtiana is a poisonous plant that grows in semi desertic areas in north and central México. It produces several substances with different toxic effects. One of them designated T-514 damages severely the lung, kidney and liver, producing in the hepatoeyte large intracellular fat deposits and necrosis. Preliminary observations demonstrated that three is a decrease in the amount of peroxisomes in the hepatocytes of experimentally intoxicated rats and monkeys. To study the effect exerted by the T-514 on peroxisomes, a yeast model was selected, thus, three species: Saccha romices cerevisiae, Ilansenula polymorpha and Candida boidinii were used, because there is information concerning their peroxisome's morphology, enzyme content, biological behaviour under different culture conditions and biogenesis.
Ultrastructural characterization of primary cultures of liver cells obtained from the Japanese medaka, Oryzias latipe
Authors: Norton W. , Garrett L. , Finch R. , Gardner H.
Published: June 2020

Nonmammalian models for investigations involving carcinogenesis have been developed as complementary extensions of current mammalian testing systems. Several species of fish, including Japanese medaka Oryzias latipes have proven to be very effective and reliable models for carcinogenesis studies, the majority of which have concentrated on hepatocellular carcinogens.

The primary objective of this investigation was to provide basic ultrastructural information regarding cultured liver cells of medaka which would be beneficial in subsequent experiments relating to the utilization of cell cultures in carcinogenesis studies. Primary cultures of cells from livers of 20 adult medaka were obtained by trypsinization of fragmented organs. Initial cell viability, as monitored by trypan blue exclusion, was determined to be greater than 95%. Cells were plated in a complete medium composed of Dulbecco's MEM supplemented with 10% fetal calf serum, 25mM HEPES buffer, 1% sodium pyruvate, 1% non-essential amino acids and antibodies. Cell density of 5.0 to 7.5x105 cells/ml was optimal.
Abnormal spermiogenesis in hybrid mice (C57BL X C3H)F1 treated with the mutagen ethyl methane sulphonate
Authors: Gallegos M.G. , Ramírez E. , González D.J.
Published: June 2020

Ethyl methane sulphonate is an agent that produces a notable elevation in the percentage of morphologically abnormal spermatozooids. Inducement of minimal defects of the hook, bicephalic, biflagellated and amorphous forms and filamentous spermatozzoids have been described. The cytotoxic effect of the drug is manifested by death of primary spermatocytes, which is associated to the low number of epididlmary spermatozooids. The mechanisms that produce teratospermia have not been previously studied exhaustively.

Hybrid mice of genotype (C57BL X C3H)F1 of 8 to 12 weeks of age were treated intraperitoneal ly with EMS at a dose of 200 mg/Kg for five consecutive days and killed four weeks later by cervical dislocation. The testicular tissue was fixed by inmersion in 6.5% glutaraldehyde in 0.2 M phosphate buffered saline at pH 7.3 and 4°C, and was included in epoxyresine. Fine sections were stained in leal citrate and uranyl acetate, and were observed in Zeiss EM109 electron microscope.
Ultrastructure of developing visual cortical synapses in the cat superior colliculus
Authors: Miller Caroline A. , Bruce Laura L.
Published: June 2020

The first visual cortical axons arrive in the cat superior colliculus by the time of birth. Adultlike receptive fields develop slowly over several weeks following birth. The developing cortical axons go through a sequence of changes before acquiring their adultlike morphology and function. To determine how these axons interact with neurons in the colliculus, cortico-collicular axons were labeled with biocytin (an anterograde neuronal tracer) and studied with electron microscopy.

Deeply anesthetized animals received 200-500 nl injections of biocytin (Sigma; 5% in phosphate buffer) in the lateral suprasylvian visual cortical area. After a 24 hr survival time, the animals were deeply anesthetized and perfused with 0.9% phosphate buffered saline followed by fixation with a solution of 1.25% glutaraldehyde and 1.0% paraformaldehyde in 0.1M phosphate buffer. The brain was sectioned transversely on a vibratome at 50 μm. The tissue was processed immediately to visualize the biocytin.
An High-voltage electron microscopic study of extracellular matrix-cell contacts in an attached collagen lattice
Authors: Tomasek J. J. , Haaksma C. J. , Song M. J.
Published: June 2020

Fibroblasts can exert tension on a surrounding substratum. Collagen lattices provide a model system for studying extracellular matrix-cell interactions that may be important in tension generation by fibroblasts. Fibroblasts cultured in an attached collagen lattice will develop tension, which results in rapid lattice retraction upon mechanical release from the underlying substratum. Thus, the cells must generate contractile force and transmit it to the surrounding matrix. Actin microfilament bundles present in fibroblasts may generate the contractile force responsible for the generation of tension. The transmission of force to the surrounding matrix could occur through a specialized transmembrane association linking actin microfilaments and fibronectin fibrils, termed the fibronexus. In this study we used the high-voltage electron microscope to examine in three-dimensions the extracellular matrix-cell contacts present at the surfaces of fibroblasts exerting tension onto the collagen lattice.
The guard mother cell dormancy of soybean cotyledon
Authors: Chou T. C. , Liu K. C.
Published: June 2020

The cotyledons of soybean seeds serve both as a food source and a photosynthetic organs for the early development of soybean seedlings. The development of the stomata of cotyledons should be important and related to the food source utilization and the mechanism of photosynthesis. During the study of the development of the cotyledon stomata of soybean seeds, a phenomenon was observed on the upper epidermal layer of the cotyledon, we call it. “the dormancy of the guard mother cell”, which is not reported in the literature available to us.

Soybean seeds were soaked, planted and sampled at 24, 48, and 72 hours after planting. The upper epidermal layers were stripped with a sharp razor blade, and processed for observation with Hitachi S-2300 scanning electron microscope.
An SEM study of the structure and classification of the leaf trichomes in the genusLycopersicon(tomato)
Authors: Gillott M. A. , Masiunas J.
Published: June 2020

Species of the genusLycopersiconcharacteristically possess pubescent leaves; seven types of trichomes were described in 1943, based on light microscopic observations. Recently, there has been renewed interest in trichomes since the presence and density of certain types of trichomes has been related to insect resistance in some species and/or varieties of tomato.

Trichomes can be divided into two functional categories, depending on whether the tips are pointed or glandular. Within each of these categories, trichome types have been further differentiated according to the length and number of cells in the stalk and the complexity of the basal structure. Three non-glandular and four glandular types have been described inLycopersicon.Our SEM observations of tomato leaf surfaces suggest that there may be a need to re-evaluate Luckwill's classification of trichome types.
Rotation of small fluorophores in cell cytoplasm measured by confocal anisotropy imaging and picosecond microfluorimetry
Authors: Verkman A.S. , Dix J.A. , Armijo M. , Fushimi K.
Published: June 2020

The Theological properties of cell cytoplasm are of importance for a number of intracellular processes including diffusion-limited enzyme reactions, intracellular vesicle trafficking, solute transport and cell motility. A wide range of cytoplasmic viscosities have been reported from fluorescence anisotropy, photobleaching recovery, tracer diffusion and electron spin resonance methods. To examine the viscosity of the fluid space between macromolecules and cytoskeletal structures in intact cells, the time-resolved picosecond motion of small fluorophores was measured. Unlike previous methods, measurements of time-resolved fluorophore motion are not confounded by probe binding to and restriction by intracellular structures.

Picosecond anisotropy decay was measured by multi-harmonic phase modulation microfluorimetry. The excitation source was a 9 watt argon laser which was impulse modulated by a Pockel's cell. Light was polarized and focused onto a < 1 μ spot on a fluorescently labelled cell. Emitted light was filtered and detected by a phase sensitive photomultiplier through a rotatable analyzing polarizer. Thirty to forty pairs of differential modulation amplitudes and phase angles were collected in parallel over the frequency range 5 to 250 MHz.
Characterization of endocytosis in intact cells by quantitative fluorescence microscopy
Authors: Maxfield Frederick R.
Published: June 2020

Endocytosis, the process by which extracellular macromolecules are taken into the cell is particularly amenable to quantitative analysis using fluorescence techniques. Fluorescently-labeled proteins and other macromolecules are taken up by cells via receptor-mediated endocytosis or fluid phase pinocytosis. Recently, fluorescent lipid probes have also been synthesized which label the endocytic pathway, allowing observation of lipid membrane traffic.

Digital imaging allows the manipulation of images, background and autofluorescence subtractions, and fluorescence intensity measurements of individual endocytic compartments. Image intensification microscopy and digital image processing have been used extensively for studies of endocytosis, including the measurements of endosome pH, and the identification and quantitation of endocytic vesicle fusion. Recently, pathways taken by endocytosed fluorescent molecules have been followed using the confocal microscope, adding a powerful tool to investigate questions about endocytosis which were very difficult to study with conventional, full-field microscopy techniques.
Flow-immunofluorescent studies of lung surfactant protein (SP-B)
Authors: Longo M. L.
Published: June 2020

Respiratory distress syndrome (RDS), a life threatening disorder, occurs if a lipid-protein complex which lines the airspaces of the lungs is compromised. Successful treatment of RDS has been reported with a vesicular dispersion containing dipalmitoylphosphatidylcholine (DPPC), egg phosphatidylglycerol (egg PG), palmitic acid and lung surfactant protein, SP-B. It has been hypothesized that amphipathic regions of SP-B are important in these synthetic lung surfactants as they serve as a point of insertion for the protein into the lipid bilayer. Therefore two amphipathic peptides, SP-B(l-25) and SP-B(49-66), were synthesized to use in reconstitution studies. The incorporation of SP-B(l-25) into lipid bilayer has been visualized using immunofluorescent tagging in a specially designed flow-chamber.
Ultrastructural changes in the rough endoplasmic reticulum and its contents following Brefeldin A treatment of human chondrocytes in vitro
Authors: Gruber H. E.
Published: June 2020

The rough endoplasmic reticulum (rER) is now recognized as a major organelle responsible for ensuring that only structurally correct and properly folded proteins are allowed to enter the cellular secretory pathway. We are especially interested in the behavior of the chondrocyte rER since ultrastructural studies of many skeletal dysplasias have revealed that electron dense material accumulates or is not degraded within the rER of chondrocytes from patients. Remodelling of the rER in chick chondrocytes has also been evaluated at the ultrastructural level and the rER found to play a role in procollagen export from the cell. We have utilized normal human chondrocytes grown in culture to investigate the role of brefeldin A, an antiviral antibiotic, which has been shown to primarily block protein transport from the ER to the Golgi complex.
A combined pre- and post-embedding double labeling in the central nervous system with good tissue preservation
Authors: Milroy A.M. , Ralston D.D.
Published: June 2020

Multiple labeling at the electron microscopic level is routinely done in various parts of the central nervous system. We demonstrate that the pre-embedding tetramethylbenzidine (TMB) reaction for visualizing horseradish peroxidase (HRP) of Olucha and the slow osmication of Henry combined with a post-embedding nonetching immunogold method will also preserve good ultrastructure. Furthermore, the post-embedding immunocytochemistry of some neurotransmitters, i.e. gammaaminobutyric acid (GABA), can be done months after the tissue has been reacted for HRP and embedded in regular epon.

Pre-embedding histochemistry:

The use of TMB as a chromagen for the demonstration of neuronally transported HRP has both the advantage of being highly sensitive and of producing very specific needle-like crystals. Olucha et al demonstrated that one could further stabilize this reaction product with amonium heptamolybdate. Unfortunately the next step, fixation with regular osmium tetroxide, often resulted in the loss of the reaction product. However, the slow osmication with a lower pH (5.5) in the phosphate buffer at room temperature as recommended by Henry et al prevented this loss, and at the same time resulted in well preserved ultrastructure.
Ultrastructural localization with Transmission Electron Microscopy of the catalytic activity of adenosine monophosphate deaminase in murine skeletal muscle
Authors: Bielat K. , Tritsch G.
Published: June 2020

AMP deaminase was visualized in a manner analogous to our previous approach with adenosine deaminase. The chloro-analog of AMP, i.e., 6 Chloropurine riboside 5’ monophosphate (CPRMP) (from Sigma) was shown to be a substrate of this enzyme which liberates Cl- is precipitate with added Ag+, electron dense Ag° grains are deposited at loci of enzyme activity. The substrate at a concentration of 1.1 mM in 50 mM HEPES buffer, pH 7.2, in the presence of 150 mM K* (as the acetate), 3mM ATP and 10μM pentostatin (deoxycoformycin) was incubated with freshly excised tissue from a female C-57 BL/6 mouse. The substrate concentration is 1.4 times Km for rabbit muscle enzyme (Sigma), and K+ and ATP are allosteric activators of this enzyme. Because many cells have ectonucleotidase activity, pentostatin was added to prevent manifestation of adenosine deaminase activity of dechlorination of any nucleoside that might be formed.
Viscosity characteristics and hardening rates for Embed 812 and LX112 with alternative anhydride and catalyst choices
Authors: Mascorro Joe A. , Kirby Gerald S.
Published: June 2020

The original formula for preparing embedding media based upon Epon 812 utilized the anhydrides DDSA and NMA and the amine catalyst DMP-30. Since Epon has not been available for many years, this traditional formula often is used for preparing similar embeddments using the many Epon 812-replacement resins. While popular and successful, this historical mix produces media with high viscosity. Epon replacements are versatile compounds that can be matched specifically with certain anhydrides and catalysts to produce final mixes with a broad range of viscosity characteristics. This present work offers information on the compatability of the resins Embed 812 and LX112 with alternate low-viscosity anhydride and catalyst components such as NSA and BDMA. In addition, the catalysts DMP-30, DMAE, and BDMA are examined specifically for their viscosity and the manner in which they affect the overall hardening characteristic of the embedding medium.
A silver methenamine method for the demonstration of biologic calcification sites
Authors: Hanker J.S. , Giammara B.L.
Published: June 2020

Much work has been carried out in our laboratories with the periodic acid-thiocarbohydrazide silver methenamine(PATS) reaction, an improved variation of the periodic acid-Schiff(PAS) or periodic acid-thiocarbohydrazide(TCH)-osmium tetroxide(PATCO) reactions. The PATS stain was used in many of our studies on the vascularization of hydroxylapatite/plaster of Paris implants for bone restoration. It was very useful in demonstrating the Type III collagen or reticulin of the pericapillary reticular network of the newly formed blood vessels. In the course of these studies the improved ability of silver methenamine solutions applied under microwave irradiation to deposit silver at sites of calcification or certain calcium compounds in our specimens was noted. Much more silver was deposited at these sites in femur sections of 5 day old mice after application of 1% silver methenamine soln (pH 9.6) for 1 min at 2450 MHZ and reducing with TCH for 30 seconds (Figs. 1,3,4) than by application of 5% silver nitrate for 30 minutes under bright light and reduction for 2 1/2 minutes with 5% sodium thiosulfate (Fig. 2).
Analysis of selenium granules in Aeromonas hydrophila
Authors: Smith N. R. , Bramlett B. J. , Echer C. , Dixon B. A.
Published: June 2020

Selenium (Se) is a naturally occurring nonmetallic element found in the environment as a result of fossil fuel combustion and industrial and agricultural processes. Although it is an essential trace element for plants and animals, high levels of soluble Se in agricultural drainage water have had deleterious effects on fish and waterfowl. The toxic forms of Se exist as selenate (+VI) and selenite (+IV) and both valence forms can be chemically reduced to insoluble, non-toxic elemental Se (O).

A number of microorganisms are capable of reducing soluble Se to the zero valence state. Models have been proposed for using indigenous bacteria in water treatment systems to remove the toxic forms of Se via the reduction process. In order to realistically utilize this procedure, it is necessary to demonstrate that indeed the soluble Se is converted to elemental Se.
Structural evaluation of biodegradability of nonwoven fabrics
Authors: Goynes W. R. , Delucca A. J. , Moreau J. P.
Published: June 2020

Disposability of nonconsumable products has become an increasing environmental concern. Convenience products are widely used in the United States, and fibrous disposables such as lightweight towels, diapers, medical supplies, and pads constitute a large share of these products. The fibrous disposables market is highly oriented to synthetic fibers, which are generally not biodegradable. In this study we evaluated differences in biodegradability of nonwoven fabrics containing cotton (C) and polypropylene (PP) fibers. It included 100% untreated cotton, blends of cotton with 20, 30, 50, and 75% polypropylene, and a chemically bonded 100% cotton. Biodegradability tests were conducted using ASTM procedure G 21-70 by exposing four replicate strips of the fabrics to combinations of fungi commonly found in soil for timed incubation periods. The fungi included Aspergillus niger, Penicillium funiculosurn, Chaetomiwn virius, and Aureobasidium pullulans. Fabric strips (2.55 cm x 17.78 cm) were placed on a medium of nutrient-salts agar in lidded bioassay dishes.