bluuebunny/crossref_metadata_2025 huggingface dataset:
Immuno-Electron Microscopic Study on the Pulmonary Metastases of Chang' s Hepatoma Cells
Authors: Chew E. C. , Sun C. N. , White H. J.
Published: June 2020

The study of tumor metastasis has long been a subject of interest in cancer research because it is one of the principal problems in malignancy that prevents successful local treatment. The purpose of this communication is to report the sequence of metastasis of Chang's hepatoma cells studied by immuno-EM techniques.

The use of peroxidase-labelled antifibrin antibody to demonstrate fibrin in early stages of metastases has been described earlier (1). Rats were killed at different time intervals, ranging from 5 minutes to 1 month after tumor cell innoculation. Small pieces of lung tissue were fixed in 4% phosphate buffered glutaraldehyde and post-fixed in 1% oxmium tetroxide. Routine procedures were followed for dehydration and embedding in Epon 812. Sections were stained with uranyl acetate and lead citrate.

The fine structure of Chang's hepatoma cells has been reported elsewhere (2,3). At 5 minutes after IV injection, tumor cells were found in the pulmonary vessels.
Cytochemical Evidence for Presynatic β-Adrenergic Regulation of Secretion in the Developing Rat Submandibular Gland
Authors: Cutler L.S.
Published: June 2020

Many studies previously have shown that the B-adrenergic agonist isoproterenol and the a-adrenergic agonist norepinephrine will stimulate secretion by the adult rat submandibular (SMG) and parotid glands. Recent data from several laboratories indicates that adrenergic agonists bind to specific receptors on the secretory cell surface and stimulate membrane associated adenylate cyclase activity which generates cyclic AMP. The production of cyclic AMP apparently initiates a cascade of events which culminates in exocytosis. During recent studies in our laboratory it was observed that the adenylate cyclase activity in plasma membrane fractions derived from the prenatal and early neonatal rat submandibular gland was retractile to stimulation by isoproterenol but was stimulated by norepinephrine. In addition, in vitro secretion studies indicated that these prenatal and neonatal glands would not secrete peroxidase in response to isoproterenol but would secrete in response to norepinephrine. In contrast to these in vitro observations, it has been shown that the injection of isoproterenol into the living newborn rat results in secretion of peroxidase by the SMG (1).
Differential Lability of Spindle Microtubules in Crane-Fly Spermatocytes
Authors: Janicke Marie A. , LaFountain James R.
Published: June 2020

A well-established property of cytoplasmic microtubules is that they rapidly depolymerize in vivo and in vitro when the temperature of the medium is dropped to 0-4°C. In the case of the mitotic spindle, which contains hundreds of microtubules, it has been shown that microtubules attached to the kinetochores of chromosomes appear to be more stable to cold shock than are the more numerous non-kinetochore microtubules, which are not attached to chromosomes (1). These results led us to inquire into the possible universality of differential lability of spindle microtubules as well as to speculate on possible factors that could give rise to this phenomenon.

Our approach was to incubate spermatocytes of crane flies (Nephrotoma suturalis) in cold Ringer's solution, fix them in cold, buffered glutaralde- hyde at intervals of 7, 15, 30 and 60 minutes after the start of cold shock, post-fix in osmium tetroxide and then process them for embedding in epoxy resin.
Demonstration of Microtubules in Type II Alveolar Cells
Authors: Stone Frederick J. , Kikkawa Yutaka
Published: June 2020

Two lines of evidence indicate a probable role for microtubules in the secretory processes of type II alveolar epithelial cells. These are: (1) The inhibition of the release of disaturated lecithins (the major component of putative type II cell secretory products) by lung slices pretreated and then incubated with antimicrotubular agents colchicine and vinblastine (Delahunty, J.J. and Johnston, J.M.: J. Lipid Res., 17:112,1976); and (2) The abnormality of the secretory granules, lamellar bodies, in the type II cells of beige mice (Chi, E.Y. Prueitt, J.L., and Lagunoff, D: J. Histochem. Cytochem., 23:863-869, 1975) in which microtubular function is abnormal (Oliver, J.M.: Amer. J. Pathol., 85:395, 1976). Our failure to morphologically identify the expected microtubules in type II cells from lungs prepared for electron microscopy by conventional fixations led us to attempt their visualization by the application of the tannic acid- glutaraldehyde fixative of Futaesakie, et. al. (Histochemistry and Cytochemistry, 1972.).
Morphological Changes in the Rat Granulosa Cell Surface During Differentiation Induced by Estradiol and Gonadotropins
Authors: Bagavandoss P. , Richards JoAnne S. , Midgley A. Rees
Published: June 2020

During follicular development in the mammalian ovary, several functional changes occur in the granulosa cells in response to steroid hormones and gonadotropins (1,2). In particular, marked changes in the content of membrane-associated receptors for the gonadotropins have been observed (1).

We report here scanning electron microscope observations of morphological changes that occur on the granulosa cell surface in response to the administration of estradiol, human follicle stimulating hormone (hFSH), and human chorionic gonadotropin (hCG).

Immature female rats that were hypophysectcmized on day 24 of age were treated in the following manner. Group 1: control groups were injected once a day with 0.1 ml phosphate buffered saline (PBS) for 3 days; group 2: estradiol (1.5 mg/0.2 ml propylene glycol) once a day for 3 days; group 3: estradiol for 3 days followed by 2 days of hFSH (1 μg/0.1 ml) twice daily, group 4: same as in group 3; group 5: same as in group 3 with a final injection of hCG (5 IU/0.1 ml) on the fifth day.
A Scanning Electron Microscopic Study of the Inner Surface Appearance of the Alveolar Capillary
Authors: Wang N.S. , Wei F. , Charbonneau M.
Published: June 2020

Capillary networks interwave with elastic fibers (1) in alveoli and are focally sleeved by myofibroblasts (2) or held apart by pillar or "posts" (3). All these structures are implicated in the regulation of the capillary flow by light and transmission electron microscopic studies. The endothelium of the alveolar capillary is also known to be active metabolical- ly. The present paper presents some morphological evidences of these implicated functions on the inner surface of the alveolar capillary.

The pulmonary artery of rabbit lungs was cannulated and perfused successively with heparinized normal saline, veronal acetate buffered 3% glutaral- dehyde solution, buffer solution without fixative, followed by saturated uranium acetate water solution at 30 cm H2O pressure while the lung was positively inflated with room air at either 5 or 15 cm H2O pressure. The hardened lungs were then sliced and dehydrated with graded acetone, cryo- fracture in liquid nitrogen, critical point processed, and examined with a scanning electron microscope.
Fine Structural Alterations in Thyroid Follicular Cells (FC) and Changes in Serum Thyroxine Produced by Feeding Polychlorinated Biphenyl (PCB) to Rats
Authors: Collins W.T. , Capen Charles C. , Kasza Louis
Published: June 2020

The widespread contamination of the environment with PCB, a compound used extensively by industry in hydraulic and heat transfer fluids as well as plasticizers and solvents in adhesives and sealants, has resulted in detectable tissue levels in a large portion of the human population, domestic animals, and wildlife. Intoxication with PCB produces severe hepatic necrosis, degeneration of lymphoid tissues and kidney, skin lesions, decreased reproductive performance, reduced feed efficiency, and decreased weight gain. PCB also has been reported to reduce the binding of thyroid hormone to serum proteins and enhance the peripheral metabolism of thyroxine with increased excretion of thyroxine-glucuronide in the bile (Bastomsky, Endocrinology 95: 1150-1155, 1974).

The objectives of this investigation were (1) to investigate the histopathologic, histochemical, and ultrastructural changes in thyroid FC produced by the acute (4 week) and chronic (12 week) administration of low (50 ppm) and high (500 ppm) doses of PCB to rats, (2) to correlate these alterations to changes in serum immunoreactive thyroxine concentration, and (3) to investigate the persistence of the effects of PCB on the thyroid gland.
Preliminary Fine Structural Observations on the Testes of Young Centrifuged Rats: Possible Correlations with Senescent Changes
Authors: Johnson J. E.
Published: June 2020

Recent data (Johnson, Mehler, and Oyama, Brain Research, 1976, 106, 205-221) indicate that centrifuging rats for varying periods of time causes fine structural alterations in their central nervous system, some of which mimic changes seen in aged animals. In furthering our studies of the effects of hypergravitational forces on cell fine structure, we have begun an examination of several other body organs in centrifuged rats. The male rats used in the present report were centrifuged for 3 to 7 weeks at 4.15 G beginning at 5 weeks of age. They were sacrificed within 1 hour after removal from the centrifuge by perfusion through the left ventricle. The fixative consisted of 1% paraformaldehyde and 1.5% glutaraldehyde in 0.1M phosphate buffer (pH 7.1 - 7.4). Tissue specimens were treated with 2% OsO4 in 0.1M phosphate buffer and embedded in Epon-8l2.
Changes in Hepatocytes During Extracorporeal Perfusion of Canine and Porcine Livers
Authors: Menz L.J. , Ruwart M.J. , Kaminski D.L.
Published: June 2020

In a study designed to evaluate the performance of isolated perfused liver, a structural-functional correlation was made which included physiological, biochemical, and ultrastructural analysis. The livers from adult dogs and young pigs were prepared for cannulation of the artery, the veins, and the bile duct while observing a minimum ischemic time of a few minutes. The perfusate consisted of heparinized, oxygenated whole blood maintained normothermic as it entered the liver via the portal vein and hepatic artery for periods ranging from 2 to 5 hours.

Throughout the perfusion, portal venous pressure was monitored, bile production was determined every 10 minutes and pyruvate output was obtained from continuous autoanalysis of perfusate before entry and after leaving the organ. Samples for electron microscopy were taken before cannulation, immediately after transfer to the perfusion apparatus (15 minutes post-cannulation), and every hour thereafter.
Quantitative Reduction of Desmosomes in Malignant Meningiomas
Authors: Liszczak T. , Kleinman G. , Richardson E.P. , Kornblith P.
Published: June 2020

Among the ultrastructural features that characterize human meningiomas are interdigitating cell processes connected by desmosomes which are surface specializations for intercellular relationships. These desmosomes are fairly constant in meningiomas of different histological subtypes and lend themselves to quantitative study. Occasionally invasive malignant meningiomas occur. These malignant meningiomas have surface properties different from the non-invasive tumors. In examining tissue sections from invasive and non-invasive tumors we found a reduction in the desmosome number in the malignant tumors.

Portions of tumors were placed into 2.57, glutaraldehyde in the operating room, postfixed in Dalton's chrome osmium, stained en bloc with uranyl acetate and embedded in Epon 812. Sections were lead citrate stained. For quantitation, random 200 mesh grid squares were photographed at low magnification, 3000x. The same squares were examined at 20,000x and desmosomes were counted (Dn). Since multinucleation is uncommon in meningiomas, the low magnification photographs could be examined and the number of nuclei and presumably total cell number recorded (Cn).
Extraocular Muscle Pathology in Aperts Syndrome
Authors: Pachter Bruce R. , Margolis Shelia , Davidowitz Jacob , Breinin Goodwin M.
Published: June 2020

Aperts disease or Acrocephalosyndactyly described by Apert1 consists of oxycephaly (tower skull), exophthalmos, strabismus, antimongloid fissures, syndactyly (fusion of fingers, 2-4). This syndrome frequently involves ocular motility disturbances.: the latter have been suggested to result from mechanical limitations of the globe which are secondary to the bony malformation of the orbit2. Up until this time the question of a structural abnormality existing in the extraocular muscles themselves has not been investigated. The present light and electron microscopic study examined a segment of the inferior oblique muscle taken from a patient with Aperts syndrome.

The right inferior oblique muscle from a patient with Aperts syndrome was completely disinserted and an 8mm segment was taken from its belly portion. The specimen was fixed initially in 1% paraformaldehyde-1% glutaraldehyde in phosphate buffer for 4 hrs, then transferred to 4% glutaraldehyde overnight. The muscle segment was postfixed in 1% osmium tetroxide, dehydrated in graded alcohols, embedded whole in Epon 812, and serially sectioned at 15 microns.
Histogenesis of Human Extraocular Muscles and Its Innervation
Authors: Martinez A. Julio , Barmada M.
Published: June 2020

Embryonic myogenesis and neurogenesis of human extraocular muscles (EOM) were studied by light and electron microscopy in a group of embryos and fetal specimens (6 to 24 weeks gestational age) (20 to 200 mm CR length).

The earliest trace of EOM in humans have been reported at 7 mm (4 weeks) as a single undifferentiated mass of condensed paraxial mesoderm surrounding the optic vesicle. There is no separation between individual muscles. The distinction occurs before the 20 mm stage (6-7 weeks) when the 4 recti and the 2 obliques can be recognized(1). The oculomotor nerve can be identified as an elongation of the midbrain at 12.2 mm (5th week). The trochlear nerve appears between the 6th and 7th weeks and the abducens nerve is recognizable first at 31.3 mm (8th week). By the end of the 8th week, all the nerves had reached their respective muscles.
Effect of Tocopherol Pretreatment on the Incidence of Adriamycin-Induced Murine Cardiomyopathy
Authors: Liss R.H. , Ifrim I. , Myers C.E.
Published: June 2020

Adriamycin, an important new anticancer drug, has exhibited significant chemotherapeutic activity against a wide spectrum of human neoplasms. However, this anthracycline induces an irreversible, delayed cardiac toxicity in both man and in laboratory animals. The cardiotoxicity is believed to follow peroxidation of cardiac lipid by adriamycin (1). Recently, it has been reported that both the lipid peroxidation and cardiac toxicity that follow administration of adriamycin are reduced by pretreatment with the free radical scavenger, tocopherol (2). The present study was undertaken to compare the incidence of adriamycin-induced cardiomyopathy in rodents treated with (a), the compound alone and (b), adriamycin and tocopherol.

One group of CDFp male mice received alpha-tocopherol (85 units, I.P.) 24 hours prior to the administration of adriamycin (15 mg/kg, I.P.). A second group was dosed identically with adriamycin, without tocopherol pretreatment. Both groups of mice were sacrificed 5 days following drug administration and myocardium from left ventricles was excised, fixed in glutaralde- hyde and prepared for electron microscopy.
Extended Perfusion for Long-Term Preservation of Whole Hearts
Authors: Philpott D. E. , Moretti R. L. , Harrison G. , Klein G. , Abraham S. , Kato K.
Published: June 2020

One of the problems associated with heart transplants is the maintenance of the donor heart while the recipient is being prepared. The present method, which entails keeping the body of the donor alive as a sort of incubation chamber, is expensive and difficult. Maintenance of the heart in vitro would not only cut costs, but also allow greater flexibility in recipient selection, location and timing of the operation.

To determine the effects of preparing hearts for perfusion maintenance, rat hearts were excised and prepared for retrograde perfusion via the aorta. Once excised, the hearts were cooled in iced Tyrode's solution saturated with 95% O2 and 5% CO2 during the preparation for perfusion. Warm Tyrode's (37°) containing 2% plasma was then flushed through the heart at 100mm Hg pressure for 3 min., 15 min., 30 min. and 1 hour.
Anchorfibers and the Topography of Junctional SR
Authors: Junker James , Sommer Joachim R.
Published: June 2020

Junctional sarcoplasmic reticulum (JSR) in all its forms (extended JSR, JSR of couplings, corbular SR) in both skeletal and cardiac muscle is always located at the Z - I regions of the sarcomeres. The Z tubule is a tubule of the free SR (non-specialized SR) which is consistently located at the Z lines in cardiac muscle (1). Short connections between JSR and Z lines have been described (2), and bundles of filaments at Z lines have been seen in skeletal (3) and cardiac (4) muscle. In opossum cardiac muscle, we have seen bundles of 10 nm filaments stretching across interfibrillary spaces and adjacent myofibrils with extensions to the plasma- lemma in longitudinal (Fig. 1) and transverse (Fig. 2) sections. Only an occasional single filament is seen elsewhere along a sarcomere. We propose that these filaments represent anchor fibers that maintain the observed invariant topography of the free SR and JSR throughout the contraction-relaxation cycle.
Fine Structure of Some Plethodontid (Caudata: Plethodontidae) Spermatozoan Cytoplasmic Droplets
Authors: Wortham J. W. E. , Vernick S. H. , Morrison J. E. , Patek D. R. , Thompson S. M.
Published: June 2020

Spermatozoan cytoplasmic droplets have been noted in a variety of animal species. Although their function and chemical nature is as yet undetermined, Noble and Weber (1) suggested that droplets in plethodontid salamanders are useless vestiges retained on the mature spermatozoa, while Murphy et al. (2) have suggested that the cytoplasmic droplets may play some role in sperm maturation. The object of the present study is to determine the morphology and chemical nature of these droplets at the light and electron microscopy level.

In our studies of spermatozoan cytoplasmic droplets, we used the sperm from Plethodon jordani and Desmognathus ochrophaeus (Caudata, Plethodontidae). The droplets were observed in testicular material of both species and from spermatozoa taken from the vas deferens of Desmognathus ochrophaeus, and were most often found associated with the middle piece of the spermatozoa. The droplets were limited by a single membrane and located on the side of the axial rod opposite the undulating membrane and flagellum (Fig. 1 and 2).
Ultrastructural Response of Rat Adenohypophysis to Phenothiazines
Authors: Sarphie T.C.
Published: June 2020

Phenothiazine derivatives are known to have direct actions upon the hypothalamus which influences the secretory activities of the adenohypophysis. Previous studies indicate that such derivatives as chlorpromazine, perphenazine and trifluoperazine inhibit the release of FSH and LH while facilitating the release of prolactin all of which blocks ovulation, suppresses estrous cycles, causes infertility and pseudopregnancy and induces lactation (1,2). To morphologically correlate these endocrine responses with phenothiazine treatment, this paper surveys the ultrastructural features of the gonadotrophic secretory cell types in the adenohypophyses of rats treated with the aforementioned, commercially available compounds.

Changes in the ultrastructure of the gonadotroph-secreting cells became evident after only 3 days of drug treatment with obvious increases in numbers and sizes of secretory granules accompanied by pronounced dilatation of the endoplasmic reticulum. The presence of these larger granules represents a fundamental cellular mechanism in the adenohypophysis for handling excessive hormone produced during the suppression of secretion (3).
Transmission Electron Microscopy Studies of Pore Cells in Limax Maximus
Authors: Beltz B. S.
Published: June 2020

The cells which are described in this study surround the salivary nerve of the terrestrial mollusc, Limax maximus. The salivary system of Limax consists of bilateral glands, ducts, and nerves. The salivary nerves originate at the buccal ganglia, which are situated on the posterior face of the buccal mass, and run along the salivary duct to the gland. The salivary nerve branches several times near the gland, and eventually sends processes into the gland.

The pore cells begin to appear at the first large branch point of the salivary nerve, near the gland (Figure 1). They follow the nerve distally and eventually accompany the nerve branches into the gland tissue. The cells are 20-50 microns in diameter and contain very small nuclei (1-5 microns) (Figure 2).

The cytoplasm of the pore cells is segregated into a storage area of glycogen and an organelle region located in a band around the cell periphery (Figure 3).
Effect of Contraceptive Steroids on the Endometrium of Guinea Pig: SEM study
Authors: Said Mai M. , Nayak Ramesh K. , McCoy Randall E.
Published: June 2020

Burgos and Wislocki described changes in the mucosa of the guinea pig uterus, cervix and vagina during the estrous cycle investigated by transmission electron microscopy. More recently, Moghissi and Reame reported the effects of progestational agents on the human female reproductive tract. They found drooping and shortening of cilia in norgestrel and norethindrone- treated endometria. To the best of our knowledge, no studies concerning the effects of mestranol and norethindrone given concurrently on the three-dimensional surface features on the uterine mucosa of the guinea pig have been reported. The purpose of this study was to determine the effect of mestranol and norethindrone on surface ultrastructure of guinea pig uterus by SEM.

Seventy eight animals were used in this study. They were allocated into two groups. Group 1 (20 animals) was injected intramuscularly 0.1 ml vegetable oil and served as controls.
On the Nature of Intramembrane Particles
Authors: Robertson J. David
Published: June 2020

The chemical nature of the ubiquitous ∽8-10nm intramembrane particles (IMP's) observed with freeze-fracture-etch (FFE) techniques in biological membranes has not been unequivocally established. Some believe that they represent directly metal coated solid globular protein macromolecules residing within the hydrophobic core of the lipid bilayer. The particles are clearly related to protein molecules in the membrane surface but the extent to which the protein extends into the replicated particles has not been established. The particles at least in some instances could be partly or even entirely lipid bound specifically to the protein with the polypeptide in the polar regions of the membrane. We have used two membranes to study this problem: the purple membrane ofHalobacterium halobiumand the fusiform vacuole membrane of urothelial epithelial cells (1). A complete report of these studies will be published with collaborators W. Schreil in the case of the purple membrane and J. Vergara on the urothelial membrane. One preliminary report on the purple membrane has already been published with W. Schreil (2).
Image reconstruction of low and high dose micrographs of negatively stained glutamine synthetase
Authors: Frank J. , Goldfarb W. , Kessel M.
Published: June 2020

Recent studies of biological specimens with long range crystalline order have demonstrated a significant improvement in resolution when the radiation level is of the order of 0.5e/Å2 and care is taken to sustain the specimen in an inert medium such as glucose rather than negative stain. A large class of biological molecules exists, however, which do not form crystalline arrays and where the population exhibits a random distribution of projected views.

In a preliminary communication we have demonstrated the possibility of applying a computer averaging procedure to such negatively stained individual molecules which produces the equivalent result to that of averaging over a number of unit cells in a crystal lattice. The present study extends these methods to assess the effect of electron dosage on negatively stained protein molecules by a comparison of averages of high and low dose micrographs of the same particles.

The protein chosen for study is the enzyme glutamine synthetase isolated from E. coli and purified according to Valentine.
Ultrastructural localization of soluble and insoluble 3H-methyl prednisolone as revealed by electron microscopic dry-mounting radioautography
Authors: Nagata T. , Yoshida K. , Ohno S. , Murata F.
Published: June 2020

Introduction

Since the recent improvements in both techniques and development in equipments at our laboratory or others, the dry-mounting procedures for radioautography facilitated the wide application of them for the study of soluble compounds such as nucleic acid precursors, amino acids, carbohydrates, lipids and steroids at both the light and electron microscopic levels. The purpose of this paper is to demonstrate ultrastructural localization of both soluble and insoluble 3H-labeled methyl prednisolone, a synthetic corticosteroid, by means of dry-mounting procedure at the electron microscopic level.

Materials and Methods

Mouse liver slices obtained from a male mouse and cultured HeLa cells were pulse- labeled in vitro in Eagle's MEM containing 6α-methyl prednisolone-1,2-T sodium succinate (100μCi/ml) for 1 hour.Some specimens were quickly frozen in isopentane cooled to -160°C with liquid nitrogen and freeze-dried,fixed in osmium vapour, embedded in Epon, dry-sectioned and dry-mounted according to the procedure described previously, by means of wire loops using Sakura NR-H2 emulsion containing dioctyl sodium sulfosuc- cinate in order to prevent the emulsion films from bursting while they are air dried.
Viewing specimens in air by reflected SEM
Authors: Ryoji Takahashi
Published: June 2020

Specimens in air can be observed with high resolution by reflected SEM using an environmental capsule which supports specimens under its window. To improve the imaging of specimens underlying the window, however, the effect of the window nad to be clearly investigated.

The fundamental of reflected SEM is to detect mirror-reflected electrons from the specimen. Fig.1-A shows a schematic expression of detecting reflected electrons (RE) from a simple form of specimen placed in vacuo. In this case, the incident electrons are reflected to horizontal(low-angle) and vertical (high-angle) directions. In general, the reflectivity of electron of a material is increased as the incidence angle is increased), accordingly, the low-angle RE provide the major contribution to the formation of the image of the specimen. Moreover, it is noted that low-angle RE provide contrasts due to the surface of the specimen, but high-angle RE provide contrasts due to the material or the mass of the bulk.
Electron microscopic studies on ultrathin frozen sections of lactating mouse mammary gland
Authors: Zarzycki Jan , Szroeder Joseph
Published: June 2020

The mammary gland ultrastructure in various functional states is the object of our investigations. The material prepared for electron microscopic examination by the conventional chemical methods has several limitations, the most important are the protein denaturation processes and the loss of large amounts of chemical constituents from the cells. In relevance to this,one can't be sure about a degree the observed images are adequate to the realy ultrastructure of a living cell. To avoid the disadvantages of the chemical preparation methods,some autors worked out alternative physical methods based on tissue freezing / freeze-drying, freeze-substitution, freeze-eatching techniqs/; actually the technique of cryoultraraicrotomy,i,e.cutting ultrathin sections from deep frozen specimens is assented as a complete alternative method. According to the limitations of the routine plastic embbeding methods we were interested to analize the mammary gland ultrastructure during lactation by the cryoultramicrotomy method.
Cytoskeleton and chromatin of chicken erythrocyte studied by freeze-fracture
Authors: Haggis G. H.
Published: June 2020

We have previously described a method for three-dimensionally viewing the interior of cells by SEM. Thin slices of tissue are used, or alternatively, cells in suspension are embedded in a thin layer of fibrin gel. The gels or tissue slices are infiltrated with glycerol or dimethyl sulphoxide (DMSO) to suitable concentration, rapidly frozen, fractured, and thawed into fixative solution. The fracture surface is viewed after critical point drying and gold, or gold-palladium, coating. In the present report we extend this work in two ways, first to show how varying conditions at the moment of thawing can be used to modify the structure seen, creating a miniature in vitro control system for study of the cell interior, and secondly to show that replicas from the fracture surface can be obtained for examination by TEM. Using replicas, this technique becomes an extension of the standard freeze-etch technique, but with a result equivalent to very deep etching.
Quantitative high resolution light and EM autoradiography of fluorophosphate-esterase in developing mouse liver
Authors: Budd C.
Published: June 2020

The distribution and concentration of fluorophosphate reactive (FPR) esterases in the liver of developing and adult mice was determined quantitatively from light and electron microscope autoradiograms of liver reacted with 3H - diisopropylfluorophosphate (3H-DFP) an irreversible inhibitor of carboxylesterases.

The majority of labeled cells in the liver of 2, 8, 14 and 28- day-old mice and in adult mice (60-180 days old) were hepatocytes, but in the liver from 2-day-old mice and to a lesser extent 8-day-old mice, the autoradiographic silver grains were also concentrated over granulocytes of the intrahepatic hemopoietic population.

Quantitative measurements of grain density (developed silver grains/unit area) in light microscope autoradiograms revealed an increase in the predominantly cytoplasmic concentration of FPR esterase sites in hepatocytes from 137o of the adult concentration in 2-day-old mice, to 497, and 78% of the adult concentration in 8- and 14-day-old animals, respectively.
Two- or three-way observations of the identical cell elements within the same sections by LM, TEM and/or SEM
Authors: Watari Nakazo , Hotta Yasuaki , Mabuchi Yoshio
Published: June 2020

It is very useful if we can observe the identical cell elements within the same sections by light microscopy (LM), transmission electron microscopy (TEM) and/or scanning electron microscopy (SEM) sequentially, because, the cell fine structure can not be indicated by LM, while the color is; on the other hand, the cell fine structure can be very easily observed by EM, although its color properties may not. However, there is one problem in that LM requires thick sections of over 1 μm, while EM needs very thin sections of under 100 nm. Recently, we have developed a new method to observe the same cell elements within the same plastic sections using both light and transmission (conventional or high-voltage) electron microscopes.

In this paper, we have developed two new observation methods for the identical cell elements within the same sections, both plastic-embedded and paraffin-embedded, using light microscopy, transmission electron microscopy and/or scanning electron microscopy (Fig. 1).
Improved freeze-etching of difficult specimens
Authors: Robards A.W. , Umrath W.
Published: June 2020

Freeze-etching is now a well established method of biological electron microscopy but, despite its outstanding success in many areas, it still suffers from severe technical limitations when used to study heterogeneous or otherwise intractable tissues. These limitations are mainly related to the difficulty of retaining an intact replica during dissolution of the organic debris, and can be especially acute when dealing with structures composed of many different cell types, or where there are sharp boundaries between hard and soft parts of the specimen. Such difficulties have been described in more detail elsewhere, but they usually have the result that the replica breaks up into small pieces during thawing or cleaning so that it is impossible to locate specific areas of interest.

One potential method of improving the retention of intact replicas is to provide an additional supporting layer that can be removed once the organic material has been cleaned away.
Observation of fine structure in casein micelles by means of high resolution electron microscopy
Authors: Kimura Toshiaki , Fukushima Masayoshi , Furuichi Eiichi , Adachi Koichi , Hojou Kiichi , Kanaya Koichi
Published: June 2020

For fabrication purpose an argon ion beam is produced in ion source, accelerated through a high vacuum chamber and directed with final focusing to impinge on a target.

In the biological field we have utilized ion beam sputtering to examine the sub-micelles structure of casein micelles in demineralized skimmed milk. For this purpose we employed sputtering to etch the samples and to shadow the specimens. Casein micelles are remarkably stable both in fresh milk and in properly processed concentrated milk products where they are aggregated by calcium phosphate bonds.

Raw skimmed milk, electrodialysis demineralized by using ion exchange membranes were examined. The samples were fixed in 2.45%cacodylate buffered glutaraldehyde at pH 5.9-6.8 for 2 -4 hr and post-fixed in 2% cacodylate buffered osmium tetroxide at the same pH for 2 hr. After being diluted with distilled water, the samples were picked up on microgrids.
Behaviour of the nucleolar fibrillar centres in reproducing plant cells
Authors: Medina F. J. , Rodrlguez-Garcia M.I. , Risueño M.C.
Published: June 2020

The nucleolar fibrillar centres have been described recently in animal cells and in meristematic plant cells, as a constant component of the nucleolus, corresponding to the nucleolar organizing region (NOR).

In order to find out if the nucleolar fibrillar centres represent a general nucleolar component, we have studied the nucleolus in several reproducing plant tissues (megasporocytes and megaspore from Pissum sativum and mono and bicellulate pollen grains from Allium cepa and Scilla non-scripta). In these cells the fibrillar centres have a different morphological behaviour during their development.

Female reproductive tissue

Immediately before the meiosis, the megasporocyte nucleolus has a compact and rounded aspect. The fibrillar part occupies the centre and the granular part the periphery. Inside the fibrillar part, there are clear areas containing in some cases, a dark core immersed in a grey fibrillar material (Fig. 1). A similar structure was described recently in meristematic cells. In the pachytene stage, when the nucleolus is joined to the nuclear envelope, the fibrillar centres are made up of a homogeneous fibrillar material with a medium electron density.
The ionic strength dependence of chromatin folding
Authors: Thoma F. , Koller TH.
Published: June 2020

Under a variety of electron microscope specimen preparation techniques different forms of chromatin appearance can be distinguished: beads-on-a-string, a 100 Å nucleofilament, a 250 Å fiber and a compact 300 to 500 Å fiber.

Using a standardized specimen preparation technique we wanted to find out whether there is any relation between these different forms of chromatin or not. We show that with increasing ionic strength a chromatin fiber consisting of a row of nucleo- somes progressively folds up into a solenoid-like structure with a diameter of about 300 Å.

For the preparation of chromatin for electron microscopy the avoidance of stretching artifacts during adsorption to the carbon supports is of utmost importance. The samples are fixed with 0.1% glutaraldehyde at 4°C for at least 12 hrs. The material was usually examined between 24 and 48 hrs after the onset of fixation.
Scanning transmission electron microscopy of unstained nucleosomes
Authors: Usala S. , Isaacson M. , Martin T.
Published: June 2020

Ultrastructural investigations of chromatin have centered on apparent subunits of chromatin fibers called nucleosomes, whose basic elements are 140-200 base pairs of DNA and eight histone molecules. Conventional transmission electron microscopy (CTEM) analyses of nucleosomes have dealt with stained particles or crystalline arrays and have shown the basic particle to be somewhat circular in shape of about 100Å in diameter. Coupled with diffraction studies, the models seem to indicate a disk shaped object with all the DNA surrounding a protein core. However, due to the difficulties of conventional staining techniques and the inability to grow large crystals, resolution has been limited to about 20Å.

The ability of the STEM to provide a variety of different modes of contrast should be able to surmount some of the difficulties associated with conventional electron microscopy. In fact, early work with the STEM also indicated disk shaped nucleosome particles. The ability to efficiently form images of unstained particles using either elastically or inelastically scattered electrons allows us to directly obtain the mass density distribution of the particles at resolutions near 5Å.
Contrast from epitaxially sandwiched macromolecules
Authors: Talianker M. , Brandon D.G.
Published: June 2020

A new specimen preparation technique for visualizing macromolecules by conventional transmission electron microscopy has been developed. In this technique the biopolymer-molecule is embedded in a thin monocrystalline gold foil. Such embedding can be performed in the following way: the biopolymer is deposited on an epitaxially-grown thin single-crystal gold film. The molecule is then occluded by further epitaxial growth. In such an epitaxial sandwich an occluded molecule is expected to behave as a crystal-lattice defect and give rise to contrast in the electron microscope.

The resolution of the method should be limited only by the precision with which the epitaxially grown gold reflects the details of the molecular structure and, in favorable cases, can approach the lattice resolution limit.

In order to estimate the strength of the contrast due to the void-effect arising from occlusion of the DNA-molecule in a gold crystal some calculations were performed.
Study of fetal intestinal microperoxisomes in thick sections
Authors: calvert R.
Published: June 2020

Differentiation of microperoxisomes has been studied in Swiss ICR mouse embryos from the 16th day of fetal life till birth. After fixation with glutaraldehyde, 40μm thick sections of duodenum and of ileum were incubated at pH 9.7 according to the method described by Novikoff et al. (1972), during three hours. Catalase activity was also measured by a spectrophotometric method (Lück, 1965). Thick Epon sections (0.4μm) were used to study the peculiar morphology of microperoxisomes during the last day of gestation.

The number of microperoxisomes increases considerably in the duodenal enterocytes at 17 days; the highest concentration of microperoxisomes is attained at 18 days, after which time their number remains stable. Biochemically, catalase activity is barely detected at 15 days in the first half of the small intestine and afterwards increases steadily up to one day after birth. In the ileum the increase in microperoxisome number is far less important than in the duodenal enterocytes.
Observations on globular intranuclear inclusions in the midgut cells of an insect
Authors: Thomas D. , Gouranton J.
Published: June 2020

Most nuclei of the midgut cells of Carausius morosus contain eosinophilic inclusions.
Histochemical observations on paraffin sections revealed that the inclusions were never stained by the Feulgen method and were not sudanophilic. They were lightly stained by the PAS method. No calcium could be detected in them although numerous calcified concretions were found in the cytoplasm.

In electron microscopy the inclusions appeared as roughly spherical electron-dense bodies, different in size, usually 0.1-2 μ in diameter. These spherules were sometimes seen singly but generally in clusters (Fig. 1). In some instances several dense globules coalesced to form a lobulated mass. The inclusions were never surrounded by a membrane. Around the globules and in the space between them appeared a slightly electron- dense granular material which sometimes adhered to their margins. No direct relation was observed between the inclusion and the nucleolus.

The results of cytochemical methods on thin sections were in agreement with the findings in light microscopy since carbohydrates could be detected in the inclusions by the periodic acid-thiocarbohydrazide-silver method and no DNA was found in them with the Schiff-thallium method.
Cytochemical analysis of mast cell granules after poly-dl-lysine action
Authors: Courtoy R. , Simar L.J. , Christophe J.
Published: June 2020

Several chemical compounds induce amine liberation from mast cells but do not necessarily provoque the granule expulsion. For example, poly-dl-lysine induces modifications of the cellular membrane permeability which promotes ion exchange at the level of mast cell granules. Few of them are expulsed but the majority remains in the cytoplasm and appears less dense to the electrons. A cytochemical analysis has been performed to determine the composition of these granules after the polylysine action.

We have previously reported that it was possible to demonstrate polyanions on epon thin sections using a cetylpyridinium ferric thiocyanate method. Organic bases are selectively stained with cobalt thiocyanate and the sulfhydryle groups are characterized with a silver methenamine reaction. These techniques permit to reveal the mast cell granule constituents, i.e. heparin, biogenic amines and basic proteins.
The crystalline structure in the membranous preparations of mitochondrial complex III
Authors: Asai Junpei
Published: June 2020

In 1962 Hatefi and his collegues showed biochemically the isolation of four complexes of the electron transfer chain from the mitochondria and the reconstitution of a complete electron transfer chain through re-association of the individual complexes. Tzagoloff et al demonstrated ultrastructurally the membrane formation by either single complex or a mixture of complexs. However, there have been a few direct ultrastructural studies in the molecular architecture of mitochondrial inner membrane. To understand the organization of Complex III (QH2-cytochrome c reductase) in the membrane, the membranes made from this complex under various conditions were examined ultrastructurally in the present study.

Complex III was purified from beef heart mitochondria by the method of Heatefi et al as modified by Rieske et al. For the preparations of membrane formation, some samples of the purified complex suspended in the solution contained 0.66 M sucrose were diluted with 100 volumes of the mixture of 0.25 M in sucrose and 0.01 M in Tris-HCl (sucrose-Tris), pH 8.0 and were incubated for 30 min. at 0-4°C.
Interaction of glial and astrocytoma c6 cells in monolayer culture
Authors: Wong Y.C. , Garber B.B.
Published: June 2020

The separation and culture of the glial monolayer cells have been reported. Using the differential attachment method and treatment with cytosine arabinoside (Ara-C) followed by subculturing, a very pure population of glial cells can be achieved. This paper involves the study of the interaction of the glial cells with a tumour cell line C6 astrocytoma (American Type Cell) derived from the mouse brain. In addition the differences in surface morphology of the glial cells and C6 astrocytoma are also included.

The C6 cells were cultured in a plastic culture disk using F-10 medium supplemented with 15% fetal bovine serum, 2.5% horse serum, and 1% penicillin and streptomycin (Microbiological Association). The culture medium was changed every 3-4 days. Pure glial cell cultures were prepared as reported, and confluence monolayer glial cells were obtained about one month after subculturing of the primary glial cultures.
Ultrastructural and chemical evidences of heterogeneity and hormone dependence of certain glycocalyces
Authors: Monis B. , Lis D. , Parlanti I. , Eynard A. R. , Valentich M. A. , Rovasio R. A. , Boldint C. , Paschini A.
Published: June 2020

We are gathering evidences which indicate ultrastructural variations and chemical heterogeneity of certain glycocalyces as well as hormone dependence of some of them. Thus, in the lumenal glycocalyx of renal collecting tubules of the guinea-pig granular and filamentous structures were seen (1, fig. 1). By isolation, chemical analysis and cellulose acetate electrophoresis in various buffers of tubular membrane material, glycopeptides and glycosaminoglycans were identified (fig. 2).

Guinea-pig and rat transitional epithelium of urinary tract showed a filamentous lumenal glycocalyx demonstrable with ruthenium red (fig. 3) but which only in part stained with concanavalin A. Chemical and electrophoretic data indicated that urothelium contains glycoproteins, glycosaminoglycans and glycolipids.

The glycocalyx of the fat globule membrane of milk of several species has a granular appearance as shown by cationic dyes and by concanavalin A (2, 3, fig. 4 and 5). Also, several glycoproteins were isolated and identified on polyacrilamide gel electrophoresis (fig. 6). Glycosaminoglycans and certain glycolipids such as sulfatides were chemically identified in this glycocalyx.
Sem visualization of surface charges as a new method
Authors: Veres I.
Published: June 2020

The transmissional electronoptical measurement of the electrical surface charges of biomembranes was a part of the new trend of research work “ultramicrobiophisics” introduced by the Author.

Recently we succeeded in effecting a quasi three - dimensional visualization by using a modified SEM-technique combined with a colloid labeling method, working as guest - professor at the Uni. of Minnesota, USA. This proved to be a substantial progress: we could study in this way the dispersion of the coulombic forces on entire cell surfaces in contrast with ultrathin sectioning of labeled cells.

Objects are prefixed using 1% solution of Glutar- Aldehyde, then they are labeled with positively or negatively charged colloid AgI solution, newly prepared by using o, o2 M solutions of AgNO3and KI. Therafter the labeled and washed objects are dried in a series of ethanol and twice in Dimethyl- Propilenoxide under centrifugation. The dispersion of the surface charges is measured by counting the adsorbed sol particles on the SEM micrograph and / or using microanalyzer resp. electron microprobe.
Development of the tight junctions. do the particles participate in the initial formation of the junction?
Authors: Suzuki Fumie , Nagano Toshio
Published: June 2020

To clarify how the cell membrane and its particles behave in the initial formation of the tight junctions (Tjs), the abdominal mesothelium of mouse fetuses (12 to 19-day of gestation) and fetal Sertoli cells of the mouse and human were studied by freeze-fractured replica and thin sectioning. In the mouse mesothelium of 12-13 day embryos, the cell membranes of the junctional domain are closely apposed forming belt-like meshworks in the adluminal area. No tight junctional particles can be observed in the meshworks on both fractured faces which show linear elevations on the P face and the grooves on the E face (Fig. 1). This is termed the type I of Tj, tentatively. The type II Tjs consist of discontinuous particles located on the linear elevations on the P face (Fig. 3). The continuous strands with smooth surface on the elevations of the P face are also observed. This is refered to type III (Figs. 2, 3, 4).