bluuebunny/crossref_metadata_2025 huggingface dataset:
CYTOCHEMISTRY AND ELECTRON MICROSCOPY
Authors: Sabatini David D. , Bensch Klaus , Barrnett Russell J.
Published: May 2004

The aldehydes introduced in this paper and the more appropriate concentrations for their general use as fixatives are: 4 to 6.5 per cent glutaraldehyde, 4 per cent glyoxal, 12.5 per cent hydroxyadipaldehyde, 10 per cent crotonaldehyde, 5 per cent pyruvic aldehyde, 10 per cent acetaldehyde, and 5 per cent methacrolein. These were prepared as cacodylate- or phosphate-buffered solutions (0.1 to 0.2 M, pH 6.5 to 7.6) that, with the exception of glutaraldehyde, contained sucrose (0.22 to 0.55 M). After fixation of from 0.5 hour to 24 hours, the blocks were stored in cold (4°C) buffer (0.1 M) plus sucrose (0.22 M). This material was used for enzyme histochemistry, for electron microscopy (both with and without a second fixation with 1 or 2 per cent osmium tetroxide) after Epon embedding, and for the combination of the two techniques. After fixation in aldehyde, membranous differentiations of the cell were not apparent and the nuclear structure differed from that commonly observed with osmium tetroxide. A postfixation in osmium tetroxide, even after long periods of storage, developed an image that—notable in the case of glutaraldehyde—was largely indistinguishable from that of tissues fixed under optimal conditions with osmium tetroxide alone. Aliesterase, acetylcholinesterase, alkaline phosphatase, acid phosphatase, 5-nucleotidase, adenosine triphosphatase, and DPNH and TPNH diaphorase activities were demonstrable histochemically after most of the fixatives. Cytochrome oxidase, succinic dehydrogenase, and glucose-6-phosphatase were retained after hydroxyaldipaldehyde and, to a lesser extent, after glyoxal fixation. The final product of the activity of several of the above-mentioned enzymes was localized in relation to the fine structure. For this purpose the double fixation procedure was used, selecting in each case the appropriate aldehyde.
ISOLATION OF RAT PITUITARY GRANULES AND THE STUDY OF THEIR BIOCHEMICAL PROPERTIES AND HORMONAL ACTIVITIES
Authors: Hymer W. C. , McShan W. H.
Published: May 2004

A simple and rapid method is described for the isolation of the acidophilic and basophilic granules from the anterior pituitary gland of the rat. The method involves chromatography of pituitary particulates on columns of No. 545 Celite equilibrated and developed with 0.25 M sucrose. Mitochondria are retained quantitatively on the column. The granules and microsomes which are not retained on the Celite are further fractionated on a discontinuous density sucrose gradient and by differential centrifugation. Essentially homogeneous populations of acidophilic and basophilic granules were obtained as indicated by 1) extensive electron microscopic studies, 2) enzymatic determinations, and 3) fatty acid and RNA analyses on the granule pellets. Microfiltration studies indicated that the acidophilic granules were smaller than 450 mµ, but greater than 300 mµ in diameter. They were found, unlike the basophilic granules, to be partially stable to extraction with water, but were unstable on incubation in 1 mM EDTA at 37°. Magnesium ions were not detected in the granules. The acidophilic and basophilic granules contained, respectively, 5 and 8 per cent of the protein present in the whole homogenate. Extensive hormone studies showed that growth and lactogenic hormones were associated with the acidophilic granules, while thyroid-stimulating hormone and gonadotropin were associated with the basophilic granules. ACTH was not present in significant amounts in either of the granule fractions, but was localized in a particulate fraction which contained microsomes and small granules. The association of the pituitary hormones with specific granules and cell types is discussed.
AN INDUCIBLE ENZYME SYSTEM IN THE LARVAL CELLS OF DROSOPHILA MELANOGASTER
Authors: Rizki T. M. , Rizki Rose M.
Published: May 2004

An adaptive increase in tryptophan pyrrolase activity was obtained in the cell-free extracts of Drosophila melanogaster larvae which were given a dietary supplement of L-tryptophan. This activity was detectable in the extracts prepared from larval fatbodies when these were isolated from the remaining body tissues, but the present methods did not reveal any activity in extracts from the latter. These experiments confirm previous observations on the cellular distribution of kynurenine after feeding experiments with tryptophan. The autofluorescence characteristic of kynurenine in the larval fatbody is limited to the cells of the anterior region under normal feeding conditions, but, when larvae are fed tryptophan, autofluorescent kynurenine globules are found in a larger number of fat cells. In vitro incubation of isolated posterior fat cells with tryptophan has shown that these cells are capable of producing kynurenine. It is this same region of the fatbody in the suppressor of vermilion mutant that develops kynurenine autofluorescence, thus indicating that the absence of kynurenine in these cells in the normal strain is the result of an inhibition of their genetic potential to produce kynurenine. It has been concluded that the differentiation of "kynurenine cells" in the fatbody is controlled by a genetic mechanism which operates through the inducible tryptophan pyrrolase system.
THE USE OF BISMUTH AS AN ELECTRON STAIN FOR NUCLEIC ACIDS
Authors: Albersheim Peter , Killias Ursula
Published: May 2004

Evidence is presented to show that bismuth combines in vitro with the phosphate of nucleic acids in a manner similar to its reaction with inorganic phosphate. When tested under similar conditions, protein exhibited no attraction for bismuth. The results of the in vitro experiments, which are of interest within themselves, may be indirectly applicable to in vivo staining. Dividing cells of onion root tips were fixed in OsO4, stained with bismuth, and examined in the electron microscope. The electron opacity of cell structures known to contain nucleic acids was enhanced by bismuth, while organelles known to lack appreciable quantities of DNA or RNA showed little, if any, change. Bismuth is particularly effective as a stain for the chromatin material during interphase and for the chromosomes during division.
THE FINE LOCALIZATION OF NUCLEOSIDE TRIPHOSPHATASE ACTIVITY IN THE RETINA OF THE FROG
Authors: Scarpelli Dante G. , Craig Elson L.
Published: May 2004

Nucleoside triphosphatase (NTPase) activity was demonstrated at the submicroscopic level in the frog retina by the Wachstein-Meisel method utilizing various purine and pyrimidine nucleosides. Under the electron microscope magnesium-activated NTPase was localized in the outer and inner segments, and in the plexiform layers. NTPase active sites in the cones were localized diffusely in the 70 to 80 A interspaces between the double membranes of the stacked lamellae and in the investing cytoplasm. In the rods, on the other hand, sites of activity were observed at the periphery of the stacked lamellae as discrete electron opaque deposits measuring 1000 to 1500 A which interdigitated between the lamellae for short distances. Deposits of reaction product appeared more numerous in rods of dark-adapted frogs stimulated with monochromatic light with a wave length of 510 mµ. Enzyme activity was also observed in mitochondria of the rod and cone ellipsoids. In the outer and inner plexiform layers NTPase active sites were present on and between the membranes of axons and the plasma membranes of some of the neurons.
QUANTITATIVE STUDIES OF THE GROWTH OF MOUSE EMBRYO CELLS IN CULTURE AND THEIR DEVELOPMENT INTO ESTABLISHED LINES
Authors: Todaro George J. , Green Howard
Published: May 2004

Disaggregated mouse embryo cells, grown in monolayers, underwent a progressive decline in growth rate upon successive transfer, the rapidity of the decline depending, among other things, on the inoculation density. Nevertheless, nearly all cultures developed into established lines within 3 months of culture. The first sign of the emergence of an established line was the ability of the cells to maintain a constant or rising potential growth rate. This occurred while the cultures were morphologically unchanged. The growth rate continued to increase until it equaled or exceeded that of the original culture. The early established cells showed an increasing metabolic autonomy, as indicated by decreasing dependence on cell-to-cell feeding. It is suggested that the process of establishment involves an alteration in cell permeability properties. Chromosome studies indicated that the cells responsible for the upturn in growth rate were diploid, but later the population shifted to the tetraploid range, often very rapidly. Still later, marker chromosomes appeared. Different lines acquired different properties, depending on the culture conditions employed; one line developed which is extremely sensitive to contact inhibition.
THE EFFECTS OF CARBON MONOXIDE INHIBITION ON ATP LEVEL AND THE RATE OF MITOSIS IN THE SEA URCHIN EGG
Authors: Epel David
Published: May 2004

The requirements for ATP synthesis during the various phases of mitosis were investigated in the oxygen-requiring eggs of the sea urchin, Strongylocentrotus purpuratus. CO in the dark, a specific inhibitor of respiration, was used to inhibit ATP synthesis. The kinetics of respiratory inhibition were determined by analyzing ATP levels with the luciferin-luciferase assay. The kinetics of mitotic inhibition were determined by analysis of the rate of mitosis. It was found that CO inhibition resulted in a decrease in the normal ATP level. Coincident with this decrease was a decrease in the rate of mitosis which stops completely when the ATP drops below 50 per cent of the normal level. With the use of various degrees of CO inhibition, the rate of mitosis is shown to be related to the resultant ATP level. These results contradict the basic premise of the energy reservoir hypothesis, and also disagree with other reports that cells in mitosis are insensitive to inhibitors of energy metabolism. Data are presented which demonstrate that these conflicting reports result from insufficient inhibition of ATP synthesis. The above findings all indicate that mitosis depends on the continuous synthesis and utilization of ATP.
METABOLIC PATTERNS IN THREE TYPES OF PHAGOCYTIZING CELLS
Authors: Oren Rachel , Farnham Ann E. , Saito Kazuhisa , Milofsky Eva , Karnovsky Manfred L.
Published: May 2004

Some chemical and metabolic characteristics of polymorphonuclear leukocytes and monocytes from peritoneal exudates of the guinea pig, and of alveolar macrophages from the same animal, have been compared. Changes in the metabolic patterns of these three types of cell have been followed during the act of phagocytosis. The effect of conventional inhibitors of metabolism, and of anaerobiosis on the phagocytic ability of each of the three cell types mentioned has also been determined. From these studies it was found that alveolar macrophages depend to a considerable degree upon oxidative phosphorylation to provide energy for phagocytosis. The other two types of cell depend only on glycolysis as the source of metabolic energy for that function. In some experiments aimed at obtaining information on the possible role of complex lipids in the function of the cell membrane, it was noted that phagocytosis stimulated the incorporation of inorganic phosphate-P32 into the phosphatides of both types of cell from peritoneal exudates—whether these were free-swimming or adherent to a surface. This phenomenon has not yet been detected in the case of alveolar macrophages.
IDENTIFICATION OF THE ADRENOCORTICOTROPHIN-PRODUCING CELLS IN THE RAT HYPOPHYSIS BY AUTORADIOGRAPHY
Authors: Siperstein Eleanor R.
Published: May 2004

The relative rates of protein (hormone) synthesis and secretion by the various cell types in the anterior hypophysis of the rat have been studied by means of autoradiography. Normal and adrenalectomized male rats were injected with tritiated glycine and their hypophyses removed and fixed at 20, 40, and 90 minutes and 15 hours after injection. Autoradiograms of the hypophysial sections were prepared and autoradiographic grains were counted in the film overlying the cytoplasm of individual cells. With the aid of this method, a unique cell type was identified in the hypophyses of adrenalectomized rats. This cell is morphologically distinct from "gonadectomy cells," "thyroidectomy cells," and from previously described normal cell types, and is therefore designated as the "adrenalectomy cell." Among the 7 cell types differentiated in this study, the "adrenalectomy cell" had the highest tritium content and, in addition, at the time intervals studied this cell had the fastest rate of appearance and disappearance of protein tritium. This autoradiographic evidence of rapid protein (or polypeptide) turnover following adrenalectomy indicates that the "adrenalectomy cell" is the site of adrenocorticotrophin production in the adrenalectomized rat. Further autoradiographic and cytological evidence is presented which suggests that the "adrenalectomy cells" may be derived from chromophobes, and that a portion of the "large chromophobes" as defined in this study may be the site of adrenocorticotrophin production in the normal rat.
THE DEMONSTRATION OF ENZYMATIC ACTIVITY IN PINOCYTIC VESICLES OF BLOOD CAPILLARIES WITH THE ELECTRON MICROSCOPE
Authors: Marchesi V. T. , Barrnett R. J.
Published: May 2004

In aldehyde-fixed myocardium, enzymatic activity to nucleotide substrates was localized to the pinocytic vesicles of blood capillaries with the electron microscope. No other structures of the endothelial cell showed activity under the conditions employed. These findings are discussed in relation to recent concepts of transport across the capillary wall.
SUBMICROSCOPIC ORGANIZATION OF THE POSTSYNAPTIC MEMBRANE IN THE MYONEURAL JUNCTION
Authors: Csillik Bertalan
Published: May 2004

Cross-striated muscles of frogs and rats were fixed in 3.3 per cent lead nitrate solution. Frozen sections 30 micra thick were mounted in different media and observed by polarization microscopy. The subneural apparatus of myoneural junctions exhibits a strong birefringence in these sections. Birefringence is exerted by a highly organized lipoprotein framework (postsynaptic material) which builds up the "organites" (junctional folds) of the postsynaptic membrane. Synaptic cholinesterase is closely associated with this material. Freezing and/or formalin fixation results in a destruction of the molecular organization of the postsynaptic material, but does not influence the synaptic enzyme activity. It is hypothesized from this study that the junctional folds (postsynaptic "organites") consist of regularly arranged, sheet-like lamellar micellae in the frog and of less regular, mainly radially arranged submicroscopic units in the rat. The micellar organization as revealed by polarization analysis is in good agreement with the electron microscopic findings reported in the literature. Intramicellar protein molecules of the resting postsynaptic membrane are arranged longitudinally, lipids transversely. Supramaximal stimulation or treatment with acetylcholine + eserine results in a disorganization of proteins and a rearrangement of lipids. Denervation results in a rearrangement of lipids without any significant alterations of proteins. All these functional stresses influence only the molecular and not the micellar structure of the membrane. The function of the organized lipoprotein framework as an acetylcholine receptor is suggested.
CRYSTAL GROWTH IN RAT ENAMEL
Authors: Nylen M. U. , Eanes E. D. , Omnell K.-Å.
Published: May 2004

Observations have been made, using electron microscopy and x-ray diffraction, on the changes in crystal size and shape which occur in developing rodent enamel during mineralization. Small enamel pieces isolated from ground sections of rat molars and incisors were either embedded in methacrylate and sectioned with a diamond knife for electron microscopy, or they were mounted intact on glass fibers in a Debye-Sherrer type powder camera for x-ray diffraction. By either approach it was found that the apatite crystals were very long in the c axis direction from the beginning of enamel mineralization. Morphologically, the early crystals took the shape of extremely thin, long plates arranged in such a manner that there seemed to be little room for any further length-wise growth. It was demonstrated clearly, on the other hand, that the crystals increased in both thickness and width with advancing mineralization. As a result, the thin crystal plates gradually developed into hexagonal rods, which in the most mature enamel examined measured 500 to 600 A in width and 250 to 300 A in thickness.
STUDIES ON AMPHIBIAN YOLK
Authors: Karasaki Shuichi
Published: May 2004

The yolk platelets of mature eggs and young embryonic cells of all amphibian species studied (Rana pipiens, Triturus pyrrhogaster, Diemictylus viridescens, Rana nigromaculata, and Bufo vulgaris) have a superficial layer of fine particles or fibrils (ca. 50 A in diameter), a central main body with a crystalline lattice structure, and an enclosing membrane approximately 70 A in thickness. Electron micrographs of the main body reveal hexagonal net (spacing ca. 70 A), square net (spacing ca. 80 A), and parallel band (spacing from 35 to 100 A but most frequent at ca. 70 A) patterns. The crystalline structure is believed to be a simple hexagonal lattice made of closely packed cylindrical rods. Each rod is estimated to be about 80 A in diameter and 160 A in length.
STUDIES ON AMPHIBIAN YOLK
Authors: Wallace Robin A. , Karasaki Shuichi
Published: May 2004

Previous methods which employed simple sucrose or salt solutions to isolate yolk platelets have failed to preserve their superficial layer, and the preparations obtained generally exhibit some contamination when observed with the light or electron microscope. When yolk platelets are suspended in a sucrose-polyvinylpyrrolidinone medium, however, they remain relatively intact and their superficial layer is not lost to the medium. A method, which takes advantage of this fact, is described for the isolation of frog (Rana pipiens) yolk platelets which are free from nuclear contamination and practically free from cytoplasmic contamination. After such platelets are treated with distilled water, the superficial layer is no longer seen and a new dense and granular matrix is frequently found surrounding the crystalline main body. The significance of this and other observations concerning the effects of calcium and ethylenediamine tetraacetate are discussed.
LOCALIZATION OF THIAMINE PYROPHOSPHATASE ACTIVITY IN THE GOLGI APPARATUS OF A MOLLUSC, HELIX ASPERSA
Authors: Meek G. A. , Bradbury S.
Published: May 2004

Spermatids of the snail Helix aspersa were studied after fixation in buffered osmium tetroxide and after applying Novikoff and Goldfischer's method (15) for demonstrating thiamine pyrophosphatase (TPPase) activity both with the light and the electron microscope. The appearance of cells in the light microscope after localizing the enzyme is very similar to the appearance after the application of classical Golgi techniques. The electron microscope shows the "dictyosomes" to consist of non-granular membranes, vesicles, and vacuoles typical of the ultrastructure of the Golgi apparatus. Sites of TPPase activity are localized by deposits of lead phosphate, and are found between the membranes of the Golgi apparatus, in the small vesicles, in multivesicular bodies often found associated with it, but not within the large Golgi vacuoles. Heavy deposits are found on the caudal part of the nuclear envelope, but not in the acrosomal granule. It is suggested that TPPase may act as an intermediary in acrosome formation by the Golgi apparatus or "acroblast" of this cell. The finding of diphosphatase activity in the Golgi apparatus of an invertebrate is suggested as additional evidence for the existence of a homology between the Golgi apparatus of all animal cells.
A NEW METHOD OF POLARIZATION MICROSCOPIC ANALYSIS
Authors: Allen Robert D. , Brault James , Moore Robert D.
Published: May 2004

A new method of polarized light analysis is described in which a highly sensitive electronic detector specific for birefringence is used to identify the crystalline axes of an object and then measure its phase retardation due to birefringence. The microscopic system employed in the method consists of an electronic birefringence detection system (BDS), a microscope with strain-free lenses, and a driven stage for passing the specimen at appropriate velocities across the image of an aperture placed at the field stop and imaged in the specimen plane by the condenser. The detector registers retardations directly as voltage at a constant deflection sensitivity of ca. 1.1 v per angstrom unit over a range of 120 angstrom units. The basal rms noise level is 0.002 A for a spot 36 µ in diameter formed by a 95 x, N. A. 1.25 objective pair, and increases in proportion to the reciprocal of the diameter of the scanning spot. The increase in noise with high resolution scanning can be offset by increasing the instrumental time constant, which is adjustable in decades between 0.004 and 0.4 seconds. A number of difficult problems in high extinction polarization microscopy are avoided by the use of modulated light and a rapid electronic detector. For example: (a) The measured distribution of birefringence is unaffected by the usual diffraction anomaly; therefore polarization rectifiers are not required. (b) The detector is selective for birefringence, so that there is no problem in separating contrast due to different optical properties (e.g. dichroism, light scattering). (c) The speed and sensitivity are both increased by between one and two orders of magnitude over that attainable by visual or photographic methods, thereby rendering a vast number of weakly birefringent, light-scattering, and motile objects readily analyzable for the first time with polarized light.
DYNAMICS OF ACRIDINE ORANGE-CELL INTERACTION
Authors: Robbins Elliott , Marcus Philip I.
Published: May 2004

The in vitro localization of acridine orange (AO) in living cells was monitored by means of fluorescence microscopy, quantitative cell viability studies, and photofluorimetric measurements following dye-cell interaction. The parameters, pH, time, dye concentration, and the metabolic state of the cell were found to exert a profound influence on the time course and distribution of staining. The parameters studied are mutually interdependent, and intracellular dye localization may be predictably altered by their appropriate manipulation. Conditions are defined whereby two morphologically distinct but physiologically interrelated reactions, namely, acridine orange particle (AOP) formation and cytoplasmic reddening (CR) may be caused, prevented, reversed, or modified. These results are explained in terms of the facilitation or inhibition of an intracytoplasmic dye-segregating mechanism, in turn affected by the rate of dye ingress and the physiological state of the cell. Whereas the accumulation of AO in AOP is compatible with cell viability, the appearance of CR is correlated with cell death. It is pointed out that meaningful interpretation of vital staining requires precise regulation of many parameters in the extracellular milieu. A scheme of cell compartmentalization with respect to AO is proposed to satisfactorily account for the effects of environmental variations on the distribution and ultimate fate of intracellular dye. The AOP are viewed as normally present acid phosphatase-positive multivesicular bodies.
THE ULTRASTRUCTURE OF FLAGELLAR FIBRILS
Authors: Pease Daniel C.
Published: May 2004

The tips of rat sperm tails were slightly frayed by mechanical agitation, thus exposing the fibrils, which were then studied by electron microscopy after negative staining. Only the fibrils survived this treatment. Each fibril proved to be a cylinder with a hollow core. The walls of the cylinders were made up of 10 longitudinally oriented filaments. The filaments had a markedly beaded appearance, with a repeating period of 88 A. The filament thickness (bead width) was approximately 35 to 40 A. Beads of neighboring filaments were in register with each other so that cross-linking bound the filaments together to complete the wall structure of each fibril. The center-to-center spacing from one filament to the next was 55 to 60 A. The periodicity and the diameters of the filaments make it unlikely that the filaments are related to either actin or myosin. From the way the fibrils kinked, it can be inferred that they possessed considerable mechanical strength. It is consistent with present knowledge that fibrils of the mitotic apparatus may have the same basic structure as the flagellar fibrils. Under some circumstances, pairs of fibrils separated from one another along their length, except at their extreme tips. It was apparent that there was special bridging material to be found there. In other preparations, however, the paired fibrils remained together, indicating a powerful coupling mechanism.
THE FINE STRUCTURE AND MODE OF ATTACHMENT OF THE SHEATHED FLAGELLUM OF VIBRIO METCHNIKOVII
Authors: Glauert Audrey M. , Kerridge D. , Horne R. W.
Published: May 2004

The sheathed flagellum of Vibrio metchnikovii was chosen for a study of the attachment of the flagellum to the bacterial cell. Normal and autolysed organisms and isolated flagella were studied by electron microscopy using the techniques of thin sectioning and negative staining. The sheath of the flagellum has the same layered structure as the cell wall of the bacterium, and in favourable thin sections it appears that the sheath is a continuation of the cell wall. After autolysis the sheath is usually absent and the core of the flagellum has a diameter of 120 A. Electron micrographs of autolysed bacteria negatively stained with potassium phosphotungstate show that the core ends in a basal disc just inside the plasma membrane. The basal disc is about 350 A in diameter and is thus considerably smaller than the "basal granules" described previously by other workers.
FINE STRUCTURE OF CHLORIDE CELLS FROM THREE SPECIES OF FUNDULUS
Authors: Philpott C. W. , Copeland D. E.
Published: May 2004

A morphological basis for osmoregulation in the teleosts was studied by comparing the fine structure of chloride cells found in epithelia of the gills of three species of fish: Fundulus heteroclitus which can survive in a wide range of salinities, and F. similis and F. chrysotus which are usually restricted to salt water and fresh water environments, respectively. Gills were removed from F. heteroclitus which had been laboratory adapted to either sea water or pond water. For a comparison, gills were also removed from the marine F. similis and the fresh water F. chrysotus which had been adapted to their natural environments. Gill-filaments were fixed in Millonig's phosphate buffered (pH 7.4), 1 per cent osmium tetroxide and were embedded in Epon. Thin sections of filaments were stained with lead hydroxide. The cytoplasm of chloride cells of all three species of Fundulus is heavily populated with mitochondria and is filled with tubules of the agranular endoplasmic reticulum (ER). An orderly secretory cycle was indicated for chloride cells of salt water adapted F. heteroclitus and the marine F. similis. An amorphous material is observed in the agranular ER. Its density increases towards the apical end of the cell. In the apical cytoplasm, tubules of the agranular ER appear to converge and to discharge the amorphous material into an apical cavity. Except for the actual opening of the apical cavity, the distal end of salt water adapted chloride cells is characteristically shielded from the hypertonic environment by thin cytoplasmic flanges projecting from the neighboring epithelial cells. Chloride cells of the fresh water F. chrysotus resemble chloride cells of pond water adapted F. heteroclitus, in that these cells do not have apical cavities with the functional appearance of those in the sea water adapted forms. The distal end of fresh water adapted chloride cells is typically exposed to the free surface of the gill-filament. The possible function of the cell type is discussed.
AN ELECTRON MICROSCOPE STUDY OF THE GLAND CELLS OF THE MINK ENDOMETRIUM
Authors: Enders A. C. , Enders R. K. , Schlafke S.
Published: May 2004

Portions of mink endometrium in delayed implantation, early postimplantation, and pseudo pregnancy were fixed in buffered osmium tetroxide with sucrose, or potassium permanganate. After rapid dehydration the portions of endometrium were embedded in either methacrylate or epoxy resin. Examination of the cells from the body of the glands of the endometrium of delayed implantation revealed the presence of prominent terminal bars, numerous secretion granules, and membrane discs in the apical region of the cell. In the supranuclear and infranuclear regions, mildly dilated cisternae of the endoplasmic reticulum were present, and in many cells unusually large mitochondria were seen. Numerous changes were noted in the gland cells of the post implantation stage. The endoplasmic reticulum in the basal region was extensively dilated, and the nuclei were situated more centrally. Giant mitochondria were no longer present. The large secretion granules were not present, but smaller granules were seen, especially in the Golgi region. Some of the Golgi cisternae were dilated and the pattern of parallel membranes was consequently less distinct. It is suggested that gland cells in the postimplantation and pseudopregnancy stages exhibit evidence of greater secretory activity than those in the delayed implantation stage.
SIZE AND SHAPE TRANSFORMATIONS CORRELATED WITH OXIDATIVE PHOSPHORYLATION IN MITOCHONDRIA
Authors: Packer Lester
Published: May 2004

Two types of swelling-shrinkage change manifested by isolated mammalian heart mitochondria have been studied. One type, designated as phase I or "low amplitude" swelling-shrinkage, is estimated to lead to changes in mitochondrial volume of 20 to 40 per cent, to changes in light scattering of about 30 per cent, and to changes in viscosity. These physical changes in mitochondria are brought about rapidly and reversibly by normal reactants of the respiratory chain. Their speed, specificity, and reversibility indicate that they are closely geared to the normal function of the respiratory chain and are a true reflection of a mechanochemical coupling process characteristic of the physiology of mitochondria. A second type of swelling-shrinkage mechanism, designated as phase II or "high amplitude," leads to changes in light scattering, viscosity, and mitochondrial volume which, frequently but not always, are of higher magnitude than the phase I type. Phase II swelling-shrinkage seems to be only partly under the control of the respiratory chain. Prior to the completion of phase II swelling, a stepwise loss of mitochondrial function can be identified, such as changes in the rate of substrate utilization and loss of respiratory control. Reversal of this type of swelling cannot be effected if the swelling change reaches a steady state. This type of swelling may provide cells with a mechanism for destroying mitochondrial substance.
PHOTOMETRIC EVIDENCE FOR THE OSMOTIC BEHAVIOR OF RAT LIVER MICROSOMES
Authors: Tedeschi Henry , James Joseph M. , Anthony William
Published: May 2004

Electron microscope observations are consistent with the interpretation that the elements of the endoplasmic reticulum are osmotically active in situ as well as after isolation. More recently, it has been reported that microsomal suspensions equilibrate almost completely with added C14-sucrose and that no osmotic behavior is evident from photometric data. These findings were considered at variance with the electron microscope data. However, equilibration with added label simply attests to a relatively high permeability, and, in addition, the photometric data need not be critical. Osmotic volume changes, measured photometrically, may be masked by concomitant events (e.g., changes in the refractive index of the test solutions at varying osmotic pressures, breakdown of the particles, and agglutination). For these reasons the photometric experiments were repeated. In this work, the reciprocal of optical density of microsomal suspensions was found to vary linearly with the reciprocal of concentration of the medium at constant refractive index. These changes probably correspond to osmotic volume changes, since the effect was found to be (a) independent of substance used and (b) osmotically reversible. The transmission of the suspension was found to vary with the refractive index of the medium, the concentration of particles, and the wavelength of incident light, according to relationships that are similar to or identical with those obtained for mitochondrial suspensions.
THE RELATION BETWEEN DNA SYNTHESIS AND CHROMOSOME STRUCTURE AS RESOLVED BY X-RAY DAMAGE
Authors: Evans H. J. , Savage J. R. K.
Published: May 2004

Vicia faba root tip cells were treated for short periods with tritiated thymidine, either immediately before or after exposure of roots to x-rays, and autoradiograph preparations were analysed in an attempt to test the hypothesis that chromatid type (B') aberrations are induced only in those chromosome regions that have synthesized DNA prior to x-irradiation, whereas chromosome type (B'') aberrations are induced only in unduplicated chromosome regions. Studying the relation between presence or absence of label at loci involved in aberrations, in cells irradiated at different development stages, and the pattern of labelling in cells carrying both types of aberration leads to the conclusion that B'' aberrations are induced only in unreplicated chromosome regions. Following replication, only B' aberrations are induced, but these aberrations are also induced in chromosome regions preparing to incorporate DNA. It is suggested that the doubled response of the chromosome to x-rays prior to DNA incorporation might reflect a physical separation of replicating units prior to replication. The aberration yields in damaged cells which were irradiated in G1 S, and early G2 were in the ratio of 1.0:2.0:3.2. The data indicate that the increased yield of B' in early G2 relative to S cells may be a consequence of changes in the spatial distribution of the chromosomes within the nucleus.
THE ULTRASTRUCTURE OF MAUTHNER CELL SYNAPSES AND NODES IN GOLDFISH BRAINS
Authors: Robertson J. David , Bodenheimer Thomas S. , Stage David E.
Published: May 2004

An electron microscope study of goldfish Mauthner cells is reported.1 The cell is covered by a synaptic bed ∼ 5 µ thick containing unusual amounts of extracellular matrix material in which synapses and clear glia processes are implanted. The preterminal synaptic neurites are closely invested by an interwoven layer of filament-containing satellite cell processes. The axoplasm of the club endings contains oriented mitochondria, neurofilaments, neurotubules, and relatively few synaptic vesicles. That of the boutons terminaux contains many unoriented mitochondria and is packed with synaptic vesicles and some glycogen but no neurofilaments or neurotubules. The bare axons of club endings are surrounded by a moderately abundant layer of matrix material. The synaptic membrane complex (SMC) in cross-section shows segments of closure of the synaptic cleft ∼ 0.2 to 0.5 µ long. These alternate with desmosome-like regions of about the same length in which the gap widens to ∼ 150 A and contains a condensed central stratum of dense material. Here, there are also accumulations of dense material in pre- and postsynaptic neuroplasm. The boutons show no such differentiation and the extracellular matrix is largely excluded around them. The axon cap is a dense neuropil of interwoven neural and glial elements free of myelin. It is covered by a closely packed layer of glia cells. The findings are interpreted as suggestive of electrical transmission in the club endings.
A "MICROTUBULE" IN PLANT CELL FINE STRUCTURE
Authors: Ledbetter M. C. , Porter K. R.
Published: May 2004

This paper reports an electron microscope examination of the cortices of some plant cells engaged in wall formation. Previous studies of similar material fixed in OSO4 alone have disclosed discontinuities in the plasma membrane and other evidence of inadequate fixation. After glutaraldehyde, used as a fixative in this present study, the general preservation of cortical fine structure is greatly improved. This is shown, for example, by the first evidence of slender tubules, 230 to 270 A in diameter and of indeterminate length, in plant cells of this type. They have been found in the cortical regions of cells of two angiosperms and one gymnosperm, representing all the material so far studied following this method of fixation. The tubules are identical in morphology to those also observed here in the mitotic spindles of plant cells, except that the latter have a somewhat smaller diameter. It is noted that the cortical tubules are in a favored position to govern cytoplasmic streaming and to exert an influence over the disposition of cell wall materials. In this regard it may be of some significance that the tubules just beneath the surface of the protoplast mirror the orientation of the cellulose microfibrils of the adjacent cell walls.
CELL POPULATION KINETICS OF AN OSTEOGENIC TISSUE · II
Authors: Owen Maureen , MacPherson Sheila
Published: May 2004

A study of the cell kinetics on the actively growing periosteal surface of the femur of rabbits aged 2 weeks has been continued. A single injection of tritiated thymidine was given and the rabbits killed from 1 hour to 4 days after injection. The grain count spectra of the different cell types, pre-osteoblast, osteoblast, and osteocyte, have been compared at different times after injection. The results showed evidence for the uptake of thymidine in nuclei which is not associated with cell division. A small percentage of osteoblasts was initially labeled at 1 hour and there was evidence that the majority of these had not divided by 3 or 4 days after injection. Some thymidine-labeled cells had also become osteocytes without division. Furthermore, it appeared that a considerable fraction of the initially labeled pre-osteoblasts did not divide. The S period for the pre-osteoblasts and osteoblasts was measured using a double-labeled thymidine technique.
THE VISUAL CELLS AND VISUAL PIGMENT OF THE MUDPUPPY, NECTURUS
Authors: Brown Paul K. , Gibbons I. R. , Wald George
Published: May 2004

Electron microscopy of the visual cells of the mudpuppy Necturus have revealed several new or hitherto neglected features of organization: (a) A system of deeply staining micelles in virtually crystalline array, probably located in the lamellae of the rod outer segments. These particles may contain the visual pigment, porphyropsin. Counts of the micelles, and microspectrophotometric measurements of porphyropsin in the retina and single rods yield the estimate that each lamellar micelle may contain about 50 molecules of porphyropsin. (b) Systems of about 30 cytoplasmic filaments (here called dendrites), continuous with the cytoplasm of the inner segment, and standing like a palisade about the outer segments of the rods and cones. In the rods, one such filament stands in the mouth of each of the approximately 30 deep fissures that carve the outer segment into a radial array of lobules. (c) A system of deeply staining particles in the membranes of the dendrites, and another in the membranes of the pigment epithelial processes. It is suggested that these may have a part in interchanges of material with the outer segments. The ciliary process is found to penetrate more deeply than is commonly supposed into the outer segments of the rods and cones. The edge of each double-membrane disc in rods forms a differentiated rim structure, both around the disc circumference and bordering the fissures. These anatomical arrangements are summarized in Figs. 13 and 14, and the relevant measurements in Table I. The dilution of visual pigment in Necturus rods and cones and a general consideration of their microstructures make it seem unlikely that such typically solid state processes as exciton migration or photoconduction can transport the effects of light far from the site of absorption. Excitation must, therefore, be conveyed to the receptor as a whole by some axial structure. Among axial structures, the plasma membrane is most likely to be the site of nervous excitation. The ciliary process probably plays its main role in the embryogenesis and regeneration of outer segments; and the dendrites and pigment epithelial processes in exchanges of material with the outer segments and perhaps with one another.
PROTEIN SYNTHESIS AND RNA SYNTHESIS DURING MITOSIS IN ANIMAL CELLS
Authors: Konrad Carol G.
Published: May 2004

Protein synthesis and RNA synthesis during mitosis were studied by autoradiography on mammalian tissue culture cells. Protein synthesis was followed by incubating hamster epithelial and human amnion cells for 10 or 15 minutes with phenylalanine-C14. To study RNA synthesis the hamster cells were incubated for 10 minutes with uridine-C14. Comparisons of the synthetic capacity of the interphase and mitotic cells were then made using whole cell grain counts. The rate of RNA synthesis decreased during prophase and reached a low of 13 to 16 per cent of the average interphase rate during metaphase-anaphase. Protein synthesis in the hamster cells showed a 42 per cent increase during prophase with a subsequent return to the average interphase value during metaphase-anaphase. The human amnion cells showed no significant change at prophase but there was a 52 to 56 per cent drop in phenylalanine incorporation at metaphase-anaphase as compared to the average interphase rate. Colcemide was used on the hamster cells to study the effect of a prolonged mitotic condition on protein and RNA synthesis. Under this condition, uridine incorporation was extremely low whereas phenylalanine incorporation was still relatively high. The drastic reduction of RNA synthesis observed under mitotic conditions is believed to be due to the coiled condition of the chromosomes. The lack of a comparable reduction in protein synthesis during mitosis is interpreted as evidence for the presence in these cells of a relatively stable messenger RNA.
THE LOCALIZATION BY ELECTRON MICROSCOPY OF HELA CELL SURFACE ENZYMES SPLITTING ADENOSINE TRIPHOSPHATE
Authors: Epstein M. A. , Holt S. J.
Published: May 2004

Cultures of normally proliferating Hela cells have been examined in thin sections by electron microscopy following glutaraldehyde fixation, staining in Wachstein and Meisel's adenosine triphosphate containing medium, postosmication, and embedding in an epoxy resin. The cells were stained in suspension in order to ensure uniform accessibility to reagents. Discrete localization of the enzyme reaction product (lead phosphate) was found at the plasma membranes of about half the cells, but nowhere else. It appeared in the form of an intensely electron-opaque deposit lying close against the outer surface of the cells and varying in amount from a chain of small particles to a dense band about 30 mµ in width. This opaque reaction product was present over microvilli when absent elsewhere on a cell, was heaviest where microvilli and processes were profuse, and was minimal or lacking where cell surfaces were smooth. These observations are discussed in relation to both the idea that surface enzyme activity varies with the physiological phase of individual cells in a population, and the problem of how such enzyme activity becomes manifest at a given site on a morphologically changing membrane system.
FILAMENT LENGTHS IN STRIATED MUSCLE
Authors: Page Sally G. , Huxley H. E.
Published: May 2004

Filament lengths in resting and excited frog muscles have been measured in the electron microscope, and investigations made of the changes in length that are found under different conditions, to distinguish between those changes which arise during preparation and the actual differences in the living muscles. It is concluded that all the measured differences in filament length are caused by the preparative procedures in ways that can be simply accounted for, and that the filament lengths are the same in both resting and excited muscles at all sarcomere lengths greater than 2.1 µ, viz., A filaments, 1.6 µ; I filaments, 2.05 µ. The fine periodicity visible along the I filaments also has been measured in frog, toad, and rabbit muscles and found to be 406 A.
ELECTRON MICROSCOPE STUDIES ON THE ORIGIN OF ANNULATE LAMELLAE IN OOCYTES OF NECTURUS
Authors: Kessel Richard G.
Published: May 2004

Developing oocytes, ranging from approximately 0.1 to 1.0 mm in diameter, in Necturus were studied with the electron microscope. The outer layer of the nuclear envelope is actively engaged in the formation of vesicular elements along most of its surface, especially in smaller oocytes. Groups of vesicles appear to be released into the ooplasm at about the same time, resulting in long chains of individual vesicles immediately adjacent to the nuclear membrane. This process is repeated so that chains of vesicles grouped in rather ordered ranks extend progressively into the surrounding cytoplasm. Eventually, the cytoplasm becomes more concentrated with chains of vesicles and the distance between the individual rows becomes less. Very soon after a chain of vesicles has been budded off from the nuclear membrane, fine intervesicular connections appear between certain of the vesicles comprising the rows. Several of the vesicles in a row may then fuse, forming short, flattened cisternae. Fusion of vesicles continues, individual rows of vesicles become more closely packed and, finally, regions appear in the cytoplasm which have the appearance of annulate lamellae. Further growth of the lamellae appears to occur by the progressive fusion of vesicles at the ends of those lamellae already present, as well as by the addition of other fusing rows of vesicles.
ELECTRON MICROSCOPE STUDIES OF RABIES VIRUS IN MOUSE BRAIN
Authors: Matsumoto Seiichi
Published: May 2004

The cells of brains of 2- and 3-day old mice infected with street rabies virus were examined in the electron microscope. It was observed that characteristic rod-like or elongated particles were found within a "matrix" in the cytoplasm of nerve cells and of astrocytes. These rod-like particles can be separated into two types, on the basis of slightly different morphological features. One particle is 110 to 120 mµ wide and has double-membraned coats; the other is 120 to 130 mµ wide and is covered by a single limiting membrane. The former is closely associated with the endoplasmic reticulum. The biological relationship between the two types is unknown, but both types of particles are considered to be street rabies viruses because of their structural features. It is believed that segmentation and branching of elongated particles may play a role in virus multiplication. Negri bodies appear as dense round bodies containing various coarse structures but no virus particles.
CYTOLOGICAL AND CYTOCHEMICAL PROPERTIES OF TEN ASCITES TUMORS
Authors: Love Robert , Orsi Ernest V. , Koprowski Hilary
Published: May 2004

1. The cytological and cytochemical properties of the Ehrlich tetraploid and hyperdiploid, TA3 tetraploid and diploid, Krebs 2B, sarcoma 37, MC1M, 6C3HED and DBA lymphoma, and lymphoma #1 ascites tumors at a fixed interval after transplantation are described.

2. No qualitative differences were observed in the cytochemical properties of the nucleus, nucleolus, parachromatin, parachromatin bodies, large lipide globules, lipochondria, mitochondria, and cytoplasm of the tumor cells of the 10 neoplasms.

3. Quantitative differences were noted in the cells of the 10 neoplasms. These were reflected by variation in nuclear and cytoplasmic diameter, nucleolar mode, mitotic index, incidence of gross abnormalities of mitosis, karyorrhexis, multinucleated cells, accessory micronuclei, cell clumping, and in the number and size of the large lipide globules and lipochondria of the cells.