bluuebunny/crossref_metadata_2025 huggingface dataset:
OCCURRENCE OF PHAGOSOMES AND PHAGO-LYSOSOMES IN DIFFERENT SEGMENTS OF THE NEPHRON IN RELATION TO THE REABSORPTION, TRANSPORT, DIGESTION, AND EXTRUSION OF INTRAVENOUSLY INJECTED HORSERADISH PEROXIDASE
Authors: Straus Werner
Published: May 2004

The size, number, and location of lysosomes, phagosomes, and phago-lysosomes in different segments of the proximal and distal tubules, in the collecting tubules, and in invading macrophages of the kidneys of rats were compared by staining lysosomes (acid phosphatase) red, and phagosomes (injected horseradish peroxidase) blue in separate sections, and by staining phago-lysosomes purple by successive application of the reactions for the two enzymes in the same sections. It was concluded from these observations that the absorption of the foreign protein from the lumen and its gradual digestion in large phago-lysosomes took place mainly in the cells of the proximal convoluted tubules of the outer cortex. Several segments of the proximal convoluted tubules were distinguished on the basis of differences in the size and location of the phago-lysosomes and the amounts of peroxidase ingested. The distal tubules showed, in addition to moderate numbers of phago-lysosomes, many small phagosomes in the apical and basal zones of the cells. Moderate numbers of phagosomes and phago-lysosomes were observed in the cells of the collecting tubules. Macrophages showing very large phago-lysosomes were seen in the peritubular capillaries of the medulla, after injection of peroxidase. When high doses of peroxidase were administered, enlarged phago-lysosomes, parts of which seemed to be extruded into the lumen, were formed in the terminal segments of the proximal convoluted tubules.
ON THE SITE OF SULFATION IN COLONIC GOBLET CELLS
Authors: Lane Nathan , Caro Lucien , Otero-Vilardebó Luis R. , Godman Gabriel C.
Published: May 2004

The location of bound S35 in the goblet cell of the rat colon at time points from 2 to 60 minutes after administration of S35 as sodium sulfate has been observed in vivo and in vitro by radioautographic techniques. Grains were first observed by electron microscopy over the stacked lamellae of the paranuclear part of the Golgi apparatus. The label was subsequently found associated with the supranuclear Golgi lamellae and was then seen associated with the smooth membranes limiting the mucin granules in the goblet. Finally, between ½ and 1 hour, the secreted mucus product in the crypts became radioactive. Neither mitochondria nor the endoplasmic reticulum was labeled. It is concluded that the Golgi apparatus is the organelle in which sulfation occurs.
ON THE SITE OF SULFATION IN THE CHONDROCYTE
Authors: Godman Gabriel C. , Lane Nathan
Published: May 2004

As observed autoradiographically in the cartilage of embryonic rats, radiosulfate is bound and concentrated only in vesicles of the juxtanuclear Golgi apparatus of secreting chondrocytes within 3 minutes of its presentation. From this area, vacuoles migrate peripherally and lodge in the subcortex; their sulfated contents are thence discharged via stomata to the extracellular matrix. The label, apparently often associated with microvesicles at 10 and 20 minutes, is subsequently localized in the dense contents of the larger vacuoles. Bound radiosulfate is not detectable in other organelles. It is concluded that the vesicular component of the Golgi apparatus is the actual site of sulfation. Intracellular hyaluronidase-sensitive metachromatic granules are found chiefly at the cell periphery or mantle, rarely juxtanuclear in the main Golgi zone.
A MORPHOMETRIC STUDY ON THE THICKNESS OF THE PULMONARY AIR-BLOOD BARRIER
Authors: Weibel Ewald R. , Knight Bruce W.
Published: May 2004

A reliable knowledge of the thickness of the alveolo-capillary "membrane" or air-blood barrier is of physiologic interest since it is intimately related to a quantitative estimation of such functional events as gas diffusion or tissue metabolism in the lung. The characteristic thickness of the air-blood barrier with respect to gas diffusion is its harmonic mean thickness, while the arithmetic mean thickness is related to the mass of tissue building the barrier and consuming oxygen in the lung. Two morphometric methods are proposed by which these two dimensions can be estimated from random measurements in the electron microscope in a reliable, simple, and efficient manner. By applying these methods to three rat lungs the arithmetic mean thickness of the barrier was found to measure 1.25 µ, the harmonic mean thickness, 0.57 µ. On the basis of these measurements a geometric model of the barrier in the form of a corrugated membrane was derived. Its dimensions showed close similarity to those of the natural barrier. This analysis suggested furthermore that the gas conductance of the barrier is nearly optimal if one considers the mass of tissue and the minimal barrier thickness as fixed properties which are determined by other functional requirements on the alveolo-capillary membrane.
STUDIES ON GUINEA PIG OOCYTES
Authors: Adams Eleanor C. , Hertig Arthur T.
Published: May 2004

Oocytes in primordial and primary follicles of young adult guinea pig ovaries fixed in osmium tetroxide and embedded in Epon 812, have been observed by electron microscopy. The gradual differentiation of a series of cytoplasmic organelles has been correlated with the growth in size of the oocyte and the development of the follicular wall. The most immature primordial oocyte is morphologically a simple cell consisting of a large slightly eccentric nucleus, a few large spherical mitochondria, a profusion of granular cytoplasmic vesicles, and free RNP particles. At the primary follicle stage, abundant endoplasmic reticulum, clusters of mitochondria proliferating around a rosette formation, multiple Golgi complexes, vesicular aggregates forming cortical granules, and a profusion of microvilli have been differentiated. Concentrations of cytoplasmic organelles at the periphery of the oocyte in the primary follicle suggest that it is equipped for the absorption, utilization, and intracellular transport of material delivered to its surface membrane. The juxtaposition of components of the ultrastructure during the development and growth of this large cell appears to follow a precise pattern and provides an unusual opportunity to study the interrelationships of differentiating organelles.
THE ULTRASTRUCTURE OF A MAMMALIAN CELL DURING THE MITOTIC CYCLE
Authors: Robbins Elliott , Gonatas Nicholas K.
Published: May 2004

With a technique of preselecting the mitotic cell in the living state for subsequent electron microscopy, it has been possible to examine the ultrastructure of the various stages of mitosis with greater precision than has been reported previously. The early dissolution of the nuclear envelope has been found to be preceded by a marked undulation of this structure within the nuclear "hof." This undulation appears to be intimately related to the spindle-forming activity of the centriole at this time. Marked pericentriolar osmiophilia and extensive arrays of vesicles are also prominent at this stage, the former continuing into anaphase. Progression of the cell through prophase is accompanied by a disappearance of these vesicles. A complex that first makes its appearance in prophase but becomes most prominent in metaphase is a partially membrane-bounded cluster of dense osmiophilic bodies. These clusters which have a circumferential distribution in the mitotic cell are shown to be derived from multivesicular bodies and are acid phosphatase-positive. The precise selection of cells during the various stages of anaphase has made it possible to follow chronologically the morphological features of the initiation of nuclear membrane reformation. The nuclear membrane appears to be derived from polar aggregates of endoplasmic reticulum, and the process begins less than 2 minutes after the onset of karyokinesis. While formation of the nuclear envelope is initiated on the polar aspects of the chromatin mass, envelope elements appear on the equatorial aspect long before the polar elements fuse. Apparently interfering with this fusion are continuous spindle tubules which traverse the chromatin mass in striking density at characteristic points. Several cortical changes, also most pronounced in anaphase, have been described, as has the kinetochore which is seen to good advantage only in this stage. The Golgi complex has been found to disappear both morphologically and histochemically during mitosis and to reappear rapidly in telophase. Evidence is presented which implicates the continuous spindle tubules in certain phases of chromosome movement.
STUDIES ON LYSOSOMES
Authors: Keiser Harold , Weissmann Gerald , Bernheimer Alan W.
Published: May 2004

Streptolysins S and O from hemolytic streptococci were found to induce mitochondrial swelling and the release of malic dehydrogenase from mitochondria; no other streptococcal products were as active. Mg++, cyanide, dinitrophenol, bovine serum albumin, and antimycin all inhibited streptolysin-induced mitochondrial swelling; only the latter two agents prevented release of malic dehydrogenase from the particles. The streptolysins also solubilized beta-glucuronidase from the less numerous lysosomes of mitochondrial fractions. Vitamin A induced swelling of mitochondria with release of malic dehydrogenase and, at higher concentrations, release of beta-glucuronidase. In these effects, streptolysin S and vitamin A resembled cysteine and ascorbate, which induced swelling and lysis of mitochondria together with solubilization of enzymes. In contrast, mitochondrial swelling induced by such agents as phosphate, thyroxine, or substrates was not accompanied by release of enzymes. The release of enzymes from particles is suggested as a criterion for distinguishing "lytic" agents from those which induce mitochondrial swelling dependent upon electron transport. It was possible to dissociate effects on mitochondria and lysosomes in these experiments; less streptolysin was necessary to damage lysosomes than mitochondria; the converse was found with vitamin A. Injury to mitochondria resulted from the direct action of these agents, since the lysosomal enzymes released as a consequence of their action were not capable of inducing mitochondrial swelling or release of enzymes under the conditions studied.
OBSERVATIONS ON THE FINE STRUCTURE OF LUTEIN CELLS
Authors: Enders Allen C. , Lyons W. R.
Published: May 2004

Corpus luteum formation was induced in 26-day-old rats which were subsequently hypophysectomized and injected with mammotrophic hormone (MH, LTH). Sections of corpora lutea from these animals were examined with the electron microscope and compared with similarly prepared (Caulfield's fixed, Araldite embedded) corpora from normal pregnancy and from controls, the latter consisting of corpora prior to hypophysectomy and corpora from uninjected rats 7 to 14 days after hypophysectomy. Lutein cells from corpora lutea of injected animals and of normal pregnancy are characterized by abundant, tortuous, tubular agranular endoplasmic reticulum and by mitochondria, many of which are disc-shaped with dense matrices and both villiform and lamelliform cristae. The endoplasmic reticulum is most abundant in lutein cells from pregnant animals, in which cells it is in the form of thin, highly tortuous tubules. The form of the lipid droplets seen in cells of stimulated animals varies greatly. Marginal foldings of the lutein cells on the perivascular space were found in all instances. Lutein cells from hypophysectomized animals have a less highly developed agranular endoplasmic reticulum. The mitochondria have irregular outlines and a relatively lucid matrix. The lipid droplets in these cells show less tendency to be extracted, but are not so large or abundant as in the cells of onset controls. Granules believed to contain lipid pigments are common in the lutein cells of these control animals. It is suggested that lutein cells from corpora lutea which are actively secreting progesterone may be readily distinguished from lutein cells from non-active corpora by means of the multiple characteristics enumerated. It is further suggested that mammotrophic hormone has a general effect on the metabolism of lutein cells rather than solely affecting a specific organelle, the abundance or composition of which may be the limiting factor in the production of progesterone.
THE EFFECT OF SONIC OSCILLATION ON THE STRUCTURE AND FUNCTION OF BEEF HEART MITOCHONDRIA
Authors: Stasny John T. , Crane F. L.
Published: May 2004

Sonic treatment of mitochondria from beef heart results in a distribution of variously sized particles which can be fractionated by differential centrifugation. Electron microscopic observations of negatively stained fractions shows the presence of subunits, which are "knob-like" in appearance, attached to the mitochondrial membrane and membrane derivatives. Such subunits are not completely removed from the membrane by 5 minutes of sonic treatment. However, a fraction containing singular subunits of dimensions similar to those of units attached to the mitochondrial membrane has been observed. Enzymatic activities and cytochrome contents were determined for mitochondria and the fractionated, mitochondrial membrane derivatives. A concentration of enzyme activity and cytochrome content was found in fractions sedimented at 35,300 g and 79,420 g via differential centrifugation in 2x distilled water. The fraction with the highest enzymatic activities and cytochrome content, although rich in mitochondrial membrane derivatives, is deficient in membrane-bound subunits. The fraction with the lowest enzymatic activities and cytochrome content resembles detached mitochondrial subunits when examined in the electron microscope. The biochemical data and the electron microscopic observations suggest that the mitochondrial membrane and not the subunits are responsible for electron transport activity.
THE REPLICATION TIME AND PATTERN OF CARCINOGEN-INDUCED HEPATOMA CELLS
Authors: Post Joseph , Hoffman Joseph
Published: May 2004

The replication time and pattern have been investigated in hepatoma cells induced by feeding 3'Me-DAB to male rats for 5 months. With the use of tritiated thymidine as a DNA label along with autoradiography, mitotic nuclear labeling has been studied 0.5 to 72 hours after the administration of the label. The following time intervals have been estimated: replication time, 31 hours; DNA synthesis, 17 hours; G2 plus Mitosis, 2 hours; G1, 12 hours. Only about 8 per cent of the tumor cell (interphase) population is "flash" labeled, following a single dose of 50 µC of H3TDR. This group of cells has been followed through three cycles of division. The repeated rhythmic passage of tumor cells through cell division is similar to that previously reported for normal liver cells in the growing rat. However, tumor cells have longer replication and DNA synthesis times. In addition, the several time intervals studied vary more in the tumor cell population than they do in the growing normal cell population.
IN VITRO CULTURE OF MUSCLE TISSUE FROM NORMAL, HETEROZYGOUS, AND DYSTROPHIC CHICKS
Authors: Herrmann Heinz , Klein N. W. , Albers G.
Published: May 2004

The degree of histological deterioration of the original explant and the extent of cell spreading was evaluated in cultures of pectoralis muscle from 11-day chicks. Although the frequencies of these two parameters varied with the amounts of horse serum and embryo extract added to the medium, cultures from dystrophic chicks, in comparison to those from either normal or heterozygous animals, consistently showed the largest number of explants with the most extreme forms of histological deterioration and cell spreading. At 20 per cent horse serum the cultures from heterozygous chicks showed greater frequencies of the more extensive forms of deterioration and spreading than the normal muscle explants, but at 5 per cent horse serum these two groups appeared similar. Regardless of genetic background, cultures of the pectoralis muscle from 18-day embryos and of the latissimus dorsi muscle from 11-day chicks exhibited comparable high frequencies for the maximal degrees of deterioration and spreading.
THE INCORPORATION AND FATE OF H3-TYROSINE IN THE HAIR CORTEX OF RATS OBSERVED BY RADIOAUTOGRAPHY
Authors: Sims R. T.
Published: May 2004

The incorporation of H3-tyrosine into the protein of the cells in the cortex of rat hair has been investigated by radioautography. In growing hairs, radioactivity is found in the matrix, the upper bulb, and the whole of the keratogenous zone up to the fully keratinized part of the shaft, 10 and 30 minutes after an injection of labelled tyrosine. This is unequivocal evidence of protein synthesis at these sites. There is a very precise relationship between the end of protein synthesis and the hardening of the cortical cells at the top of the keratogenous zone. The way in which the silver grains of the radioautographs are clustered indicates that at 30 minutes after the injection the isotope is distributed more evenly in the matrix and upper bulb than in the top of the keratogenous zone. Possibly this reflects a difference, at these sites, in the cell components engaged in protein synthesis, or in the proteins being synthesized. The fully keratinized and hardened part of the hair was not radioactive at 10 and 30 minutes after the injection of H3-tyrosine. The rate at which the radioactivity moves into this region shows that the hair of rats grows 0.9 mm/24 hours. Comparison of the degree of radioactivity along the growing hair in the 30-minute, 12-hour, and 36-hour materials shows conclusively that protein accumulates in the cortical cells during their keratinization. An injection of a labelled amino acid does not behave as an ideal pulse dose; consequently, the grain density over the hair cortex at 36 hours is 100 per cent larger than would be expected if an ideal pulse dose situation existed.
STRUCTURE OF THE MACULA UTRICULI WITH SPECIAL REFERENCE TO DIRECTIONAL INTERPLAY OF SENSORY RESPONSES AS REVEALED BY MORPHOLOGICAL POLARIZATION
Authors: Flock Åke
Published: May 2004

The anatomy of the labyrinth and the structure of the macula utriculi of the teleost fish (burbot) Lota vulgaris was studied by dissection, phase contrast, and electron microscopy. The innervating nerve fibers end at the bottom of the sensory cells where two types of nerve endings are found, granulated and non-granulated. The ultrastructure and organization of the sensory hair bundles are described, and the finding that the receptor cells are morphologically polarized by the presence of an asymmetrically located kinocilium in the sensory hair bundle is discussed in terms of directional sensitivity. The pattern of orientation of the hair cells in the macula utriculi was determined, revealing a complicated morphological polarization of the sensory epithelium. The findings suggest that the interplay of sensory responses is intimately related to the directional sensitivity of the receptor cells as revealed by their morphological polarization. The problem of efferent innervation is discussed, and it is concluded that the positional information signaled by the nerve fibers innervating the vestibular organs comprises an intricate pattern of interacting afferent and efferent impulses
CYTOPLASMIC DNA SYNTHESIS IN AMOEBA PROTEUS
Authors: Wolstenholme D. R. , Plaut W.
Published: May 2004

The application of electron microscope autoradiography to Amoeba proteus cells labeled with tritiated thymidine has permitted the identification of morphologically distinct particles in the cytoplasm as the sites of incorporated DNA precursor. The particles correspond to those previously described from light microscope studies, with respect to both H3Tdr incorporation and distribution in centrifugally stratified amoebae. Ingested bacteria differ from the particles, in morphology as well as in the absence of associated label. Attempts to introduce a normal particle labeling pattern by incubating amoebae with labeled sediment derived from used amoeba medium failed. The resultant conclusion, that the particles are maintained in the amoeba by self-duplication, is supported by the presence of particles in configurations suggestive of division.
SOME OBSERVATIONS ON THE FINE STRUCTURE AND METABOLIC ACTIVITY OF NORMAL AND GLYCERINATED VENTRICULAR MUSCLE OF TOAD
Authors: Nayler Winifred G. , Merrillees Neil C. R.
Published: May 2004

Fine structure, enzyme activity, and transmembrane potentials of normal and glycerinated ventricular muscle of the toad were studied. For electron microscopy, osmium tetroxide and Araldite were used. Plasma membranes are firmly attached to Z bands. Both the T system and sarcoplasmic reticulum are poorly developed. Small bodies of medium density may be lysosomes derived from the Golgi zone. Denser bodies may be catecholamine granules. Fine tubules of unknown significance, about 200 A in diameter and of considerable length, lie in conspicuous, although infrequent bundles. Glycogen and mitochondria are abundant. After weeks of extraction in 50 per cent buffered glycerol, most organelles were still present, and much of the gross damage was probably due to osmotic destruction of membranes weakened by extraction. Many mitochondria were well preserved. Plasma and nuclear membranes had diffuse outlines and tended to be broken. Considerable activity remained of the enzymes succinic dehydrogenase, cytochrome oxidase, and phosphorylase after the extraction, but decreased with prolonged soaking. The normal transmembrane potential was about 95 mv; in extracted muscle after 6 weeks it was about 35 mv. The view that glycerinated muscle is a simple system of actin and myosin is clearly wrong. The activity of other organelles still present must affect the actions of many drugs and ions experimentally added.
STUDIES ON AN EPITHELIAL (GLAND) CELL JUNCTION
Authors: Wiener Joseph , Spiro David , Loewenstein Werner R.
Published: May 2004

The surface structure of a gland epithelium (Drosophila salivary gland), particularly that at the junction between cells, was examined under the electron microscope. The junctional surface, which in the preceding paper was shown to be highly permeable to ions, has the following structural characteristics. About two-thirds of it are profusely infolded; the surface membranes of adjoining cells interdigitate and present desmosomes. The width of the intercellular space varies considerably. The remainder of the junctional surface, the third that abuts on the lumen, is rather straight. Here, the cell membranes are aligned parallel at a distance of 150 A, and interconnected at regular intervals of 100 A. The connecting material has a high electron opacity, and is about as thick as the cell membranes, but, unlike the latter, has no resolvable unit membrane structure. The surface at the cell base, which in the preceding paper was shown to be rather impermeable, is infolded and resembles the infolded junctional region. The luminal surface exhibits microvilli. Critical surface dimensions are given, and the implications of surface structure in intercellular permeability are discussed.
ALTERATIONS IN POLYRIBOSOMES DURING ERYTHROID CELL MATURATION
Authors: Rifkind Richard A. , Danon David , Marks Paul A.
Published: May 2004

This communication presents a morphological study of the changes in ribosome content and organization which occur during the maturation of erythroid cells of the phenylhydrazine-treated rabbit. Electron micrographs of thin sectioned nucleated and non-nucleated erythroid cells have been subjected to a quantitative analysis of the distribution of ribosomes as polyribosomes of various sizes and as single ribosomes. The ribosomes of nucleated erythroid cells of marrow are virtually all arranged in the polyribosome configuration consisting of clusters of 2 to 6 individual ribosomes. These cells are the most active in the erythroid series in protein biosynthesis. During maturation to the non-nucleated reticulocyte stage, found in the circulating blood, there is a decrease in protein synthesizing capacity, a fall in total ribosome content, and, more significantly, a decrease in the number and size of polyribosomes. Maturation to the ribosome-free erythrocyte, either under in vitro or in vivo conditions, entails a further decrease in protein synthesis which correlates with a progressive disaggregation of the biosynthetically active polyribosomes into smaller clusters and inactive single ribosomes. Possible models which may account for the stability of the polyribosome and for the mechanism of polyribosome dissociation are discussed.
CORRECTION OF POLYRIBOSOME DISTRIBUTIONS AS OBSERVED IN CELL SECTIONS BY ELECTRON MICROSCOPY
Authors: Perl William
Published: May 2004

Clusters of ribosomes observed by electron microscopy in thin sections of rabbit reticulocytes are of the same order of size as the section thickness of 600 A. Many of the observed clusters must therefore have been transected by the section surfaces and observed as clusters containing fewer ribosomes. A probability method of correcting for this effect is given. Comparison of the results with grid observations of ribosome distributions indicates sufficiently good agreement for application to cell section observations.
EXPERIMENTAL LATHYRISM
Authors: Tanzer Marvin L. , Hunt Ronald D.
Published: May 2004

In normal and lathyritic chick embryos bone collagen was synthesized primarily in the periosteum of the femurs, and was organized as radioactive spicules in these bones. Saline extraction of the lathyritic bones removed the radioactive spicules, although they eventually seemed to become non-extractable. Normal bone seemed to be unaffected by saline extraction. Marked variation in the degree of isotope incorporation was seen in collagenous and non-collagenous tissues. All the tissues of any one embryo, however, showed a similar degree of isotope incorporation. Tritiated ß-aminopropionitrile was diffusely distributed throughout bone and was completely removed by saline extraction. This autoradiographic study supports the postulate that a portion of extractable lathyritic collagen is recently synthesized and is organized in fibrous structures in bone.
FINE STRUCTURE OF THE PINEAL ORGANS OF THE ADULT FROG, RANA PIPIENS
Authors: Kelly Douglas E. , Smith Stuart W.
Published: May 2004

Frontal organs and epiphyses of the pineal system from the adult frog, Rana pipiens, were fixed in s-collidine-buffered osmium tetroxide, embedded in Epon 812, and examined by electron microscopy. Epiphyseal material was also fixed in a variety of ways and subjected to a series of cytochemical tests for light microscopy. An ultrastructure resembling that of lateral eye retina is confirmed in this species. Photoreceptor cells of the epiphysis and frontal organ display many cytological features similar to those of retinal rods and cones in the arrangement of their outer and inner segments and synaptic components. However, in these pineal organs the outer segments are disoriented relative to each other and may display a disarranged internal organization unlike normal retinal photoreceptors. Furthermore, other pineal outer segments often appear degenerate. Since immature stages in the development of new outer segments also appear to be present, adult pineal photoreceptors are probably engaged in a constant renewal of outer segment membranes. The evidence further suggests that macrophages are involved in phagocytosis of degenerated outer segments. Postulated photoreceptor activities and the possibility of secondary pineal functions, such as secretion, are discussed in view of current morphological and cytochemical findings.
OSMOTIC AND METABOLIC ALTERATIONS OF MITOCHONDRIAL SIZE
Authors: Lynn William S. , Fortney Sydney , Brown Rose H.
Published: May 2004

Sustained contraction (dehydration) of rat liver mitochondria can be readily produced by increasing the tonicity of the outside media, provided Ca++ is removed by EDTA, fatty acids are removed by albumin, and a source of chemical energy (mitochondrial substrate or ATP) is present. This was demonstrated both gravimetrically and turbidimetrically. It was also demonstrated that the net movement of sucrose and H2O under altered conditions of tonicity in mitochondria was dependent on the state of the mitochondria; e.g., in the presence of EDTA, diffusion was blocked, both into and out of mitochondria, whereas, in the presence of EDTA and electron-transport substrates, movement of sucrose and water out of mitochondria was increased. In the presence of Ca++, gramicidin, or fatty acids, diffusion of sucrose into and out of mitochondria is very rapid. Mitochondria obey osmotic law only after Ca++ and fatty acids are removed from them.
NEW CYTOPLASMIC COMPONENTS IN ARTERIAL ENDOTHELIA
Authors: Weibel Ewald R. , Palade George E.
Published: May 2004

A hitherto unknown rod-shaped cytoplasmic component which consists of a bundle of fine tubules, enveloped by a tightly fitted membrane, was regularly found in endothelial cells of small arteries in various organs in rat and man. It is about 0.1 µ thick, measures up to 3 µ in length, and contains several small tubules, ∼150 A thick, embedded in a dense matrix, and disposed parallel to the long axis of the rod. In some of these cells, the cisternae of the endoplasmic reticulum are greatly distended by the accumulation of a dense, finely granular material. The nature and significance of these cytoplasmic components are yet unknown.
ULTRASTRUCTURAL LOCALIZATION OF MINERAL MATTER IN BACTERIAL SPORES BY MICROINCINERATION
Authors: Thomas Richard S.
Published: May 2004

The fine localization of mineral matter in spores of Bacillus megaterium and Bacillus cereus was studied by the technique of microincineration adapted for use with the electron microscope. The specimens, which included intact and thin-sectioned spores as well as shed spore coats, were burned either in the conventional way at high temperature or by a new technique using electrically excited oxygen at nearly room temperature. The ash residues were examined by bright field, dark field, and diffraction in the electron microscope and also with the phase contrast microscope. In some cases, the specimen was previewed in both microscopes before incineration. The results do not support a previous report that the mineral elements of the spore are confined to a peripheral layer, but rather indicate that the spore core as well as the coat are mineral-rich. The cortex may be deficient in minerals, but the possibility of artifact prevents a clear decision on this point. Incinerated B. megaterium spores show a highly ordered fine structure displaying 100 A periodicity in the ash of the middle layer of the coat. The nature of this structure is discussed, as is the technique which demonstrated it. The fine definition of the ash patterns, particularly those obtained with the low-temperature, excited-oxygen technique, suggests that microincineration may be generally useful in the study of fine structure.
MAMMALIAN CHROMOSOMES IN VITRO
Authors: Hsu T. C.
Published: May 2004

The complete DNA replication sequence of the entire complement of chromosomes in the Chinese hamster may be studied by using the method of continuous H3-thymidine labeling and the method of 5-fluorodeoxyuridine block with H3-thymidine pulse labeling as relief. Many chromosomes start DNA synthesis simultaneously at multiple sites, but the sex chromosomes (the Y and the long arm of the X) begin DNA replication approximately 4.5 hours later and are the last members of the complement to finish replication. Generally, chromosomes or segments of chromosomes that begin replication early complete it early, and those which begin late, complete it late. Many chromosomes bear characteristically late replicating regions. During the last hour of the S phase, the entire Y, the long arm of the X, and chromosomes 10 and 11 are heavily labeled. The short arm of chromosome 1, long arm of chromosome 2, distal portion of chromosome 6, and short arms of chromosomes 7, 8, and 9 are moderately labeled. The long arm of chromosome 1 and the short arm of chromosome 2 also have late replicating zones or bands. The centromeres of chromosomes 4 and 5, and occasionally a band on the short arm of the X are lightly labeled.
DNA AND THE FINE STRUCTURE OF SYNAPTIC CHROMOSOMES IN THE DOMESTIC ROOSTER (GALLUS DOMESTICUS)
Authors: Coleman James R. , Moses Montrose J.
Published: May 2004

The indium trichloride method of Watson and Aldridge (38) for staining nucleic acids for electron microscopy was employed to study the relationship of DNA to the structure of the synaptinemal complex in meiotic prophase chromosomes of the domestic rooster. The selectivity of the method was demonstrated in untreated and DNase-digested testis material by comparing the distribution of indium staining in the electron microscope to Feulgen staining and ultraviolet absorption in thicker sections seen with the light microscope. Following staining by indium, DNA was found mainly in the microfibril component of the synaptinemal complex. When DNA was known to have been removed from aldehyde-fixed material by digestion with DNase, indium stainability was also lost. However, staining of the digested material with non-selective heavy metal techniques demonstrated the presence of material other than DNA in the microfibrils and showed that little alteration in appearance of the chromosome resulted from DNA removal. The two dense lateral axial elements of the synaptinemal complex, but not the central one to any extent, also contained DNA, together with non-DNA material.
THE EFFECTS OF EXTRAPERIOSTEAL INJECTIONS OF BLOOD COMPONENTS ON PERIOSTEAL CELL PROLIFERATION
Authors: Tonna Edgar A. , Cronkite Eugene P.
Published: May 2004

Following extraperiosteal injections of saline, serum, or whole blood, the synthesis of DNA in the cells of the osteogenic layer of the femora of mice was stimulated to approximately two-thirds of the level obtained by fracture of the femora. Irrespective of the material injected, the proliferative response of the cells in the periosteum was similar. These studies have shown that neither bone fracture nor direct disruption of the periosteum is necessary to induce periosteal cell proliferation since a single extraperiosteal injection of physiological saline induces DNA synthesis.
ULTRASTRUCTURE OF ISOLATED KIDNEY MITOCHONDRIA TREATED WITH PHLORIZIN AND ATP
Authors: Burgos Mario H. , Aoki Agustin , Sacerdote Fabio L.
Published: May 2004

Direct electron microscopic evidence is reported of the ultrastructure of mitochondrial membranes and compartments in mitochondria isolated in 0.5 M sucrose from the rat kidney cortex and the experimental changes they undergo with phlorizin and ATP treatment. A heterogeneous population of mitochondria is recognized under control conditions. The mitochondria appear to be of 3 main types, normal, swollen, and contracted. Under phlorizin treatment, most of the mitochondria swell in less than 15 minutes, apparently at the expense of the matrix. Treatment with ATP, on the other hand, produces, during the same time, a marked contraction of the isolated mitochondria, with many refoldings of the inner membrane and marked increase in the electron opacity of the matrix. It is concluded from these observations that mitochondrial swelling and contraction should be related mainly to the matrix content.
THE LOCALIZATION OF CHOLINESTERASE ACTIVITY IN RAT CARDIAC MUSCLE BY ELECTRON MICROSCOPY
Authors: Karnovsky Morris J.
Published: May 2004

A method has been developed for localizing sites of cholinesterase activity in rat cardiac muscle by electron microscopy. The method utilizes thiocholine esters as substrates, and is believed to be dependent on the reduction of ferricyanide to ferrocyanide by thiocholine released by enzymatic activity. The ferrocyanide thus formed is captured by copper to form fine, electron-opaque deposits of copper ferrocyanide, which sharply delineate sites of enzymatic activity at the ultrastructural level. Cholinesterase activity in formalin-fixed heart muscle was localized: (a) in longitudinal elements of the sarcoplasmic reticulum, but not in the T, or transverse, elements; and (b) in the A band, with virtually no activity noted in the M band, or in the H zone. The I band was also negative. No activity was detected in the sarcolemma, or in invaginations of the sarcolemma at the level of the Z band. The perinuclear element of the sarcoplasmic (endoplasmic) reticulum was frequently strongly positive. Activity at all sites was completely abolished by omitting the substrates, or by inhibition with eserine 10-4 M and diisopropylfluorophosphate 10-5 M. Eserine 10-5 M completely inhibited reaction in the sarcoplasmic reticulum, and virtually abolished that in the A band. These observations, together with the use of the relatively specific substrates and suitable controls to eliminate non-enzymatic staining, indicate that cholinesterase activity was being demonstrated. The activity in rat heart against different substrates was that of non-specific cholinesterases, in accordance with biochemical data. The activity in the A band was considered to be probably due to myosincholinesterase. It is proposed that the localization of cholinesterases in myocardium at the ultrastructural level should be taken into account in considering the possible functions of these myocardial enzymes, and it is hoped that knowledge of their localization will open up new avenues of approach in considering their physiological role in myocardium, which at present is not definitely known.
LYSOSOMAL ENZYMES OF RAT INTESTINAL MUCOSA
Authors: Hsu Lichu , Tappel A. L.
Published: May 2004

Six intracellular hydrolases known to be associated with lysosomes in rat liver were found in rat intestinal mucosa. The extent to which they were particulate-bound and the degree of enzyme release when the particulate fractions were suspended in hypotonic media followed the same pattern in both mucosa and liver. The specific activities of the mucosa enzymes were either comparable to or slightly smaller than those of the liver enzymes. These results suggest that the mucosa hydrolases belong to lysosome-like particles. However, differential fractionation of the mucosa indicated that the particles from the mucosa sediment at lower centrifugal forces than do those from the liver and are more heterogeneous in size, bearing a closer resemblance to kidney lysosomes. Possible physiological functions of particulate-bound digestive enzymes in intestinal mucosa are discussed.
INTRACELLULAR DISTRIBUTION OF CALCIUM IN DEVELOPING BREAST MUSCLE OF NORMAL AND DYSTROPHIC CHICKENS
Authors: Cosmos Ethel
Published: May 2004

To follow the intracellular distribution of calcium in the breast muscles of developing chickens, Ca45 was injected into the albumen of predeveloped eggs. Since the embryos were grown in a radioactive medium, a complete exchange of the isotope for its non-radioactive counterpart in muscles was accomplished. Subcellular particulates of the muscle cells were separated by the method of differential centrifugation. Analysis of the separated fractions showed that in the muscles of the 13-day embryo, when the nuclear-myofibrillar ratio is high, 65 per cent of the muscle calcium is in the nuclei. With the increased synthesis of myofibrils, the nuclear-myofibrillar ratio decreases with a concomitant fall in radioactivity. Thus, calcium was not associated with the developing myofibrils. At the time of hatching, when myofibrils perform physiological work, the highest level of calcium is in the mitochondria. This suggests that the mitochondria play a key role in the physiological activities of calcium in the cell. The microsomal fraction reaches a maximal level of calcium when the adult composition of muscle is attained. Results of investigations on dystrophic muscles show changes in the calcium distribution of the fractions as early as the 3rd week of embryonic development, which are interpreted to indicate an alteration in the protein metabolism of the cell, or an early destruction of muscle tissue. Further, alterations in the calcium content of fractions which seem to regulate the movements of this ion in the cell are discussed. A new technique for homogenizing tissues from embryos of different ages is presented.
A MITOCHONDRIAL PUMP IN THE CELLS OF THE ANAL PAPILLAE OF MOSQUITO LARVAE
Authors: Copeland Eugene
Published: May 2004

Mosquito larvae were raised to fourth instar in distilled water in order to maximally stimulate the salt-absorbing function of the anal papillae. Two exceptional features are observed, at the fine structure level, in the epithelial lining of the papillae. At the basal (cuticular) surface of the cells, the cell membrane is thrown into deep, narrow, parallel folds. The folds not only follow a rigid pattern at the cellular level but are also arranged at right angles to the long axis of the entire organ. A complicated pattern of canaliculi connects to the distal (plasma) surface of the cells. At this surface, paired mitochondria (sometimes triplets) are clamped about the membranes of the canaliculi to form structures referred to as "mitochondrial pumps." Mitochondria are also oriented in rather precise relation to the basal folds. Glycogen granules are found throughout the cytoplasm. The endoplasmic reticulum is sparse. The Golgi zones are flew and not well developed. Unidentifiable, irregular vesicles with lipid-like membranes are found associated with the basal folds. The distal (plasma) surfaces of the cells are covered by a homogeneous granular layer the composition of which is unknown.
CYTOPLASMIC MICROTUBULES IN DIFFERENT ANIMAL CELLS
Authors: de-Thé Guy
Published: May 2004

In avian, murine, and human cells fixed with glutaraldehyde, cytoplasmic microtubules 180 to 250 A in diameter and of undetermined length were found. These cytoplasmic microtubules are similar to those described by Ledbetter and Porter in plant cells after the same glutaraldehyde fixation. The cytoplasmic microtubules in animal cells are connected with the satellites of the centrioles and are similar to the mitotic spindle fibers. Their protein nature and their possible role in maintaining the shape of the cells are discussed. Their presence in all examined animal cells as well as in plant cells favors the hypothesis that they are a permanent component of the cytoplasm.
THE FINE STRUCTURE OF THE RAT CEREBELLUM
Authors: Herndon Robert M.
Published: May 2004

This paper describes the fine structure of the granule cells, stellate neurons, astrocytes, Bergmann glia, oligodendrocytes, and microglia of the rat cerebellum after fixation by perfusion with buffered 1 per cent osmium tetroxide. Criteria are given for differentiating the various cell types, and the findings are correlated with previous light microscope and electron microscope studies of the cerebellum.
THE DEVELOPMENT OF BASAL BODIES AND FLAGELLA IN ALLOMYCES ARBUSCULUS
Authors: Renaud Fernando L. , Swift Hewson
Published: May 2004

The development of basal bodies and flagella in the water mold Allomyces arbusculus has been studied with the electron microscope. A small pre-existing centriole, about 160 mµ in length, was found in an inpocketing of the nuclear membrane in the vegetative hypha. Thus, formation of a basal body does not occur de novo. When the hyphal tip started to differentiate into gametangia, the centrioles were found to exist in pairs. One of the members of the pair then grew distally to more than three times its original length, whereas the other remained the same size. The larger centriole would correspond to the basal body of a future gamete. Gametogenesis was usually induced by transferring a "ripe" culture to distilled water. Shortly after this was done, a few vesicles were pinched off from the cell membrane of the gametangium and came in contact with the basal body. Apparently, they fused and formed a large primary vesicle. The flagellum then started to grow by invaginating into it. Flagellar fibers were evident from the very beginning. As the flagellum grew so did the vesicle by fusion with secondary vesicles, thus coming to form the flagellar sheath. The different stages of flagellar morphogenesis are described and the possible interrelationships with other processes are discussed.
STUDIES IN EXPERIMENTAL EOSINOPHILIA
Authors: Litt Mortimer
Published: May 2004

A method is described whereby immune complexes may be visualized in a single cell. Bovine serum albumin labeled with a red-fluorescing dye was joined to a rabbit antiserum labeled with a green-fluorescing dye to yield an immune complex which fluoresced yellow when illuminated by ultraviolet light. Such yellow-fluorescing immune complexes were injected into the peritoneal cavity of guinea pigs, and the peritoneal exudates were examined subsequently. Yellow fluorescent particles were seen in eosinophils obtained from guinea pigs sensitized to hemocyanin and from normal animals. Eosinophils of the blood and of the bone marrow could also take up the complexes in vitro. Neither antigen nor antibody alone was taken up by eosinophils, nor was a mixture of labeled antigen and labeled normal globulin. Similar observations were made with human blood eosinophils. These experiments suggest that eosinophils act as part of the defense against the pathogenic effects of certain immune complexes.
CYTOCHEMICAL LOCALIZATION OF ADENOSINE TRIPHOSPHATASE IN THE MITOTIC APPARATUS OF HELA AND SARCOMA 180 TISSUE CULTURE CELLS
Authors: Hartmann John F.
Published: May 2004

ATPase was localized in distinct regions of the mitotic apparatus of HeLa and Sarcoma 180 tissue culture cells. ATPase was demonstrated in the metaphase spindle of HeLa and Sarcoma 180 cells fixed in cold buffered 2 per cent formalin (pH 6.5 to 6.8) containing 2 x 10-3 M CaCl2. A high concentration of ATPase was frequently observed at the poles of the spindle. ATPase was also demonstrated in the interzonal region of both cell types during anaphase. The narrowing of the band of ATPase activity localized in the interzonal region during telophase indicates that ATPase activity is associated with the central spindle. In polar views of Sarcoma 180 cells fixed in cold, unbuffered, 2 per cent formalin, ATPase was frequently localized in granules in the region of the inner circumference of the ring of chromosomes formed at metaphase. ATPase in the mitotic apparatus of HeLa and Sarcoma 180 cells was shown not to be due to non-specific alkaline phosphatase. Mitotic apparatus ATPase in Sarcoma 180 cells was suppressed by an —SH inhibitor.
A STUDY OF THE STRUCTURE AND DISTRIBUTION OF THE NEXUS
Authors: Dewey M. M. , Barr L.
Published: May 2004

Nexuses, that is, fusions of plasma membranes of adjacent cells, are described in mammalian smooth and cardiac muscle, median giant axon of earthworm, frog skin, and rat submandibular gland. In smooth muscle they usually occur where a process from one cell either meets a process of, or projects into a neighboring cell. On the other hand, in mammalian heart muscle and in earthworm giant axon the nexuses occur along the intercalated disc and intercellular segmental septa, respectively. Their occurrence between these excitable cells is correlated with propagation of action potentials by an electrical rather than chemical mechanism. Since the nexuses may offer pathways for electric current between cell interiors, it seems possible that they constitute a link in the structural basis for electrical transmission in these systems. In epithelia, nexuses usually appear as part of a terminal bar complex. This is true in the rat salivary gland studied here. In the epidermis of frog skin, nexuses are less numerous between the basilar columnar cells than between the subjacent squamous cells. The nexuses which occur in epithelia in frog skin and rat salivary gland are distributed as though to provide seals against electrochemical backleaks and sites of chemical exchange between cell interiors.