bluuebunny/crossref_metadata_2025_split huggingface dataset:
THE FINE STRUCTURE OF THE GALL BLADDER EPITHELIUM OF THE MOUSE
Authors: Yamada Eichi 
Published: May 2004

Sections of mouse gall bladder epithelium fixed by perfusion with buffered osmium tetroxide have been studied in the electron microscope as an example of simple columnar epithelium.
The free surface presents many microvilli, each presenting a dense tip, the capitulum, and displaying a radiating corona of delicate filaments, the antennulae microvillares. Very small pit-like depressions, representing caveolae intracellulares, are encountered along the cell membrane of the microvilli.
The free cell surface between microvilli shows larger cave-like depressions, likewise representing caveolae intracellulares, containing a dense material.
The lateral cell borders are extensively folded into pleats, which do not interdigitate extensively with corresponding folds of the adjacent cell membrane.
The terminal bars are shown to consist of thickened densities of the cell membrane itself in the region of insertion of the lateral cell wall with the free cell surface. This thickening is associated with an accumulation of dense cytoplasmic material in the immediate vicinity. The terminal bar is thus largely a cytoplasmic and cell membrane structure, rather than being primarily intercellular in nature.
The basal cell membrane is relatively straight except for a conical eminence near the center of the cell, projecting slightly into the underlying tunica propria. The basal cell membrane itself is overlain by a delicate limiting membrane, which does not follow the lateral contours of the cell.
Unmyelinated intercellular nerve terminals with synaptic vesicles have been encountered between the lateral walls of epithelial cells.
A division of the gall bladder epithelial cell into five zones according to Ferner has been found to be convenient for this study.
The following cytoplasmic components have been noted, and their distribution and appearance described: dense absorption granules, mitochondria, Golgi or agranular membranes, endoplasmic reticulum or ergastoplasm, ring figures, and irregular dense bodies, perhaps lipoid in nature. The nucleus of these cells is also described.
THE INTRACELLULAR DISTRIBUTION AND HETEROGENEITY OF RIBONUCLEIC ACID IN STARFISH OOCYTES
Authors: Edström Jan-Erik , Grampp Wolfgang , Schor Norberto 
Published: May 2004

A study has been made of the content and composition of RNA in cytoplasm, nucleoplasm, and nucleoli from growing oocytes of the starfish Asterias rubens. The determinations were carried out, using ultramicrochemical methods, on units isolated by microdissection from fixed sections. Macrochemical and interferometric control experiments show that RNA can be quantitatively evaluated in this way.
The results show that the growing oocyte represents a system in which the relations between the quantities of nucleolar, nucleoplasmic, and cytoplasmic RNA undergo great changes. These changes are continuous for nucleolar and cytoplasmic RNA so that their amounts may be predicted from the size of the cell. Nucleoplasmic RNA, on the other hand, shows great variations among different cells, independent of cell size.
Purine-pyrimidine analyses show that each cell component contains an RNA which differs significantly from that of the other two. Cytoplasmic and nucleolar RNA are closely related, the only difference being a slightly higher guanine/uracil quotient for the nucleolar RNA. They are both of the usual tissue RNA type, i.e., they show a preponderance of guanine and cytosine over adenine and uracil. Nucleoplasmic RNA deviates grossly from the RNA of the other two components. Here the concentrations of adenine and uracil are higher than those of guanine and cytosine, respectively. This RNA consequently shows some resemblance to the general type of animal DNA although the purine/pyrimidine ratio is far from unity.
Our data favor a nucleolar origin for the stable part of the ribosomal RNA and a nucleoplasmic one for the unstable part (the messenger RNA).
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.
TURNOVER OF S35-SULFATE IN THE MUCOSA OF THE GASTROINTESTINAL TRACT OF RATS AS SEEN IN AUTORADIOGRAMS
Authors: Dziewiatkowski Dominic D. 
Published: May 2004

Segments of the gastrointestinal tract removed from rats after intervals of time following injection of S35-sulfate were fixed in aqueous formalin and then washed in water. Contact and coated autoradiograms were prepared. The suggestion made by others that more of the labelled sulfate is fixed by the mucosa than by the underlying coats of the gastrointestinal tract is confirmed. In addition it was found that the isotope is fixed to a greater extent in the lower intestine than in the middle or upper portions of it.
Coated autoradiograms revealed that 6 hours after administration of S35-sulfate more of the label was present in the goblet cells lying deep in the crypts of the mucosa than in those adjacent to the intestinal lumen. By the 24th hour the concentration of the isotope was strikingly higher and more uniform from cell to cell. The mucus in the intestinal lumen was also highly radioactive. At the end of 48 hours very little of the sulfur-35 remained in the intestinal wall or could be made out in the mucus of the lumen: the autoradiographic reaction was faint and diffuse as contrasted with the punctiform and intense reaction given by the specimens removed at the end of shorter intervals of time.
ELECTRON MICROSCOPICAL STUDY OF SKELETAL MUSCLE DURING ISOTONIC (AFTERLOAD) AND ISOMETRIC CONTRACTION
Authors: Knappeis G. G. , Carlsen F. 
Published: May 2004

Bundles of the curarized semitendinosus muscle of the frog were fixed during isotonic (afterload) and isometric contraction and the length of the A and I bands investigated by electron microscopy.
The sarcomere length, during afterload contraction initiated at 25 per cent stretch, varied depending on the afterload applied between 3.0 and 1.2 µ, i.e. the shortening amounted to 5 to 50 per cent. The shortening involved both the A and I bands. Between a sarcomere length of 3.0 to 1.7 µ (shortening 5 to 35 per cent) the A bands remained practically constant at about 1.5 µ (6 to 8 per cent shortening); the length of the I bands decreased from 1.4 to 0.3 µ (80 per cent shortening). Below a sarcomere length of 1.7 to 1.2 µ the A bands shortened from 1.5 to 1.0 µ (from 6 to 8 to 25 per cent). At sarcomere lengths 1.6 to 1.2 µ the I band was replaced by a contraction band.
During isometric contraction the A bands shortened by about 8 to 10 per cent; the I bands were correspondingly elongated.
THE ULTRASTRUCTURE OF MOUSE LUNG GENERAL ARCHITECTURE OF CAPILLARY AND ALVEOLAR WALLS
Authors: Karrer H. E. 
Published: May 2004

The general architecture of capillary and alveolar walls of the mouse lung was studied by means of the electron microscope. In order to minimize tissue damage and to improve the cutting properties of embeddings, several modifications in the tissue processing methods were adopted. These modifications were: fixation by infusion, a prolonged time of dehydration, of impregnation, and of polymerization, the use of acetone for dehydration, ammonium sulfide treatment of the fixed and washed tissue, and an elevated (80°C.) polymerization temperature combined with the use of prepolymerized methacrylate. The generally favorable effects of these modified methods upon preservation and cutting properties of embedded tissue are discussed.
Both capillary endothelium and alveolar epithelium were found continuous and without pores. The endothelium was seen to be thinnest in those portions that were adjacent to alveolar air spaces. Two morphological "types" of alveolar epithelial cells were found. One protruded into the alveolar lumen with its thick portion containing the nucleus. The other was often located in a niche of the alveolar wall, and contained peculiar dark inclusions amidst numerous mitochondria. Both were attenuated at their periphery to form the thin epithelial layer. The layer between endothelium and epithelium was designated as basement membrane. It was seen to be generally thin and structureless, but was found thickened in some areas where it also contained collagen fibrils.
AN ELECTRON MICROSCOPE STUDY OF THE EPITHELIUM IN THE NORMAL MATURE AND IMMATURE MOUSE CORNEA
Authors: Sheldon Huntington 
Published: May 2004

1. An electron microscope study at high resolution of the corneal epithelium of the normal mature and immature mouse revealed new information regarding the submicroscopic appearance of these cells.
2. Two thin dense lines separated by a less dense area constituted the structure of the limiting surface membrane of epithelial cells; the thickness of this membrane was about 80 A.
3. Some differences in the appearance of the cytoplasm and mitochondria of cells from the immature mouse cornea and the appearance of the cytoplasm and mitochondria of cells from the adult mouse cornea were observed.
4. The basement membrane appeared as a dense band about 600 A wide separating the basal epithelial cells from the substantia propria. Suggestions of periodicity were seen in some phosphotungstic acid-treated specimens.
5. Round bodies believed to be bacteria were seen on the surface of the outer epithelial cells in the adult mouse cornea but not in the immature, unopened eye.
ELECTRON MICROSCOPY OF LYSOSOME-RICH FRACTIONS FROM RAT LIVER
Authors: Novikoff Alex B. , Beaufay H. , de Duve C. 
Published: May 2004

A preliminary electron microscope study has revealed the presence in lysosome-rich fractions, isolated from rat liver, of hitherto undescribed cytoplasmic particles, called "dense bodies."
Approximately 0.37 µ in length, the dense bodies often possess an internal cavity and external membrane. They contain many electron-dense granules 55 to 77 A, or less, in diameter.
Such dense bodies are also visible in electron micrographs of parenchymatous cells in liver sections.
The correlations between dense bodies and lysosomes are listed, but until pure preparations are available it is not possible to assert that dense bodies and lysosomes are identical.
PHYSIOLOGICALLY INDUCED CHANGES IN ADRENOCORTICAL MITOCHONDRIA
Authors: Lever J. D. 
Published: May 2004

1. Adrenocortical mitochondria contain filamentous or saccular internal membranes and are probably the sites of lipide elaboration or accumulation. They are numerous in the stimulated gland and scanty after hypophysectomy. There is evidence that they are expendable: light cells contain numbers of irregularly vacuolated and broken mitochondria with disorganized internal membranes.
2. Openings have been observed in some mitochondrial limiting membranes, particularly in the stimulated hamster and rat adrenal cortices, but to a lesser extent in the unstimulated glands.
3. Similarities between mitochondrial and Golgi membranes suggest a possible mode of mitochondrial formation.
4. These findings have been interrelated and discussed.
MITOCHONDRIA IN LIVING CELLS: AN ANALYSIS OF MOVEMENTS
Authors: Tobioka Motohiko , Biesele John J. 
Published: May 2004

Time-lapse cinephotomicrography of mouse embryonic fibroblasts before and shortly after perfusion of tissue cultures reveals that the elongation of mitochondria caused by coenzyme A results from the terminal association of many shorter rods into a smaller number of long filaments. These are not permanent associations, but they reflect an exaggeration of the cohesive tendency of mitochondria, which in untreated cells is counterbalanced by frequent disjoinings and breakings of the anastomotic network.
Our own observations and a survey of the literature suggest that elongate mitochondria with rapid movement and high metabolic activity tend to accompany proliferation in tissue cultures, and that mitotic inhibition of cultured cells may go together with short, slow mitochondria of low metabolic activity.
The movement of mitochondria may be both active, reflecting metabolic exchanges with the cytoplasm, and passive, the result of hyaloplasmic currents.
STUDIES ON THE GOLGI APPARATUS BY ELECTRON MICROSCOPY WITH PARTICULAR REFERENCE TO AOYAMA'S TECHNIQUE
Authors: Lacy Dennis , Challice Cyril E. 
Published: May 2004

1. Aoyama's silver impregnation method for the Golgi apparatus has been used on exocrine cells of the pancreas of the mouse and studied by electron microscopy in order to determine as precisely as possible where the silver is deposited. Similar cells have also been fixed in buffered osmium tetroxide solution and compared with cells treated by the silver technique.
2. Examination of the Aoyama preparations usually revealed a light deposition of silver in the cytoplasm (hyaloplasm or matrix) and a heavy deposition of silver around a series of closely apposed vacuoles. The heavy deposition of silver was regarded as revealing the chromophilic region of the Golgi apparatus while the vacuoles were identified as the chromophobic component.
3. Comparison of the silver preparations with those fixed in buffered osmium tetroxide solution showed that the silver was primarily deposited in the region of the Golgi membranes.
MICROSOMAL NUCLEOPROTEIN PARTICLES FROM PEA SEEDLINGS
Authors: Ts'o Paul O. P. , Bonner James , Vinograd Jerome 
Published: May 2004

Ultracentrifugal analysis of an extract of pea epicotyls, previously freed of debris and larger particles by centrifugation at 40,000 g for 10 minutes, has revealed the presence of a major component which possesses a sedimentation coefficient of 74 S. This component constitutes about 25 per cent of the TCA-precipitable material in the clarified epicotyl extract and is estimated to make up 1 to 2 per cent of the dry weight of the original tissue. In size, chemical composition, and morphology, the 74 S component resembles the nucleoproteins of the microsomes from animal tissues.
The 74 S component of pea epicotyl extracts has been purified by repeated cycles of differential centrifugation to yield a preparation which is 80 per cent homogeneous in the analytical ultracentrifuge. It has been found to contain 30 to 37 per cent RNA as judged by a variety of analytical techniques. Approximately 55 per cent of the weight of the material is protein and a further 4.5 per cent phospholipide.
Electron micrographs of air-dried specimens of the purified preparation show the 74 S constituent to be flattened spheres with an average height of 180 A and an average diameter of approximately 280 A. The molecular weight of the 74 S particles is computed from sedimentation, viscosity, and partial specific volume data to be 4.5 million ± 10 per cent in agreement with the value estimated from electron micrographs.
The 74 S or microsomal component of pea epicotyls is rapidly aggregated in the presence of low concentrations of Mg ions or by somewhat higher concentrations of Ca or K salts. ATP on the contrary causes resolution of electrolyte-induced microsomal aggregates with simultaneous degradation of the particles to an ultracentrifugally inhomogeneous mixture of lower molecular weight materials.
SUBMICROSCOPIC CHANGES OF THE SYNAPSE AFTER NERVE SECTION IN THE ACOUSTIC GANGLION OF THE GUINEA PIG. AN ELECTRON MICROSCOPE STUDY
Authors: De Robertis Eduardo 
Published: May 2004

The degenerative changes of the synaptic regions after nerve section have been studied with the electron microscope in the interneuronal synapse of the ventral ganglion of the acoustic nerve of the guinea pig. Fixation with buffered osmic tetroxide was carried out 22, 44, and 48 hours after destruction of the cochlea on one side; the contralateral ganglion being used as control.
The submicroscopic organization of normal axosomatic and axodendritic synapses is described. In the synaptic ending four morphological components are recognized: the membrane, the mitochondria, the synaptic vesicles (19, 20), and the cytoplasmic matrix. The intimate contact of glial processes with the endings and with the surface of the nerve cell is described. At the level of the synaptic junction there is a direct contact of the limiting membranes of the ending and of the cell body or dendrite. Both contacting membranes constitute the synaptic one with a total thickness of about 250 A. This membrane has regions of higher electron density where the synaptic vesicles come into intimate contact and fuse with it.
Definite degenerative submicroscopic changes in the nerve endings were observed after 22 hours of destruction of the cochlea and were much more conspicuous after 44 and 48 hours. After 22 hours there is swelling of the ending and decreased electron density of the matrix. Most synaptic vesicles have disappeared or seem to undergo a process of clumping and dissolution. Some mitochondria also show signs of degeneration. After 44 hours the synaptic vesicles have practically disappeared; mitochondria are in different stages of lysis; the membrane of the ending becomes irregular in shape, and there is shrinkage and in some cases detachment of the ending. No changes in the postsynaptic cytoplasm were observed.
These observations and particularly the rapid lysis of the synaptic vesicles are discussed in correlation with data from the literature indicating the early alteration of synaptic function and the biochemical changes occurring after section of the afferent nerve. The hypothesis that the synaptic vesicles may be carriers of acetylcholine or other active substances (19, 20) and that they may act as biochemical units in synaptic transmission is also discussed.2
CHANGE IN ENZYME ACTIVITY AND RIBONUCLEIC ACID CONCENTRATION WITHIN THE EPIDERMAL CELL OF THE RAT DURING THE GROWTH STAGE OF THE HAIR CYCLE
Authors: Griesemer Robert D. 
Published: May 2004

The rat hair cycle produces rapid anatomical and physiological changes in the entire skin. By the 4th day of the cycle, the epidermis has doubled in thickness.
The present study shows that, during this proliferative period, there is a correlation between the biological state (growth) and the molecular composition (enzyme concentrations) of the epidermal cell. In proliferated 4th day epidermis there has occurred not only an increase in the number of viable cells but also an increase in succinic dehydrogenase and cytochrome oxidase activity and ribonucleic acid (RNA) content in the viable epidermal cell. Moreover, RNA content and enzyme activities appear to be correlated.
The significance of these findings is discussed in the light of recent evidence supporting the relationship between RNA and enzyme synthesis and the role of hormones in the induction of enzyme adaptation.
ELECTRON MICROSCOPIC OBSERVATIONS OF THE CENTRAL NERVOUS SYSTEM
Authors: Luse Sarah A. 
Published: May 2004

In order to establish criteria for the identification of the neural and glial cells of the central nervous system, sections of the brains and spinal cords of mice, rabbits, guinea pigs, and rats; and portions of tumors of the human brain have been examined by electron microscopy.
Identification of neurons is made possible by the characteristic cytoplasmic picture, in which there is a distinct granular and less constant membranous ergastoplasmic pattern. In no other cell of the central nervous system is such a distinct granular component present in the ergastoplasm. The shape of the neuron in electron microscopic preparations is similar to that seen by light microscopy with several dendrites containing a similar cytoplasm arising from the perikaryon. Synapses are relatively common on the surface of the neuron and its dendrites.
Microglial cells are relatively small and dense with few processes, and are arranged as perineuronal and perivascular satellites for the most part. Occasionally phagocytized material is present in their cytoplasm. The oligodendroglial cells are identifiable by their position as perineuronal satellites and in the white matter as cells arranged in rows. They have a uniformly round to ovoid nucleus with a pale cytoplasm, which has a sparse, finely granular component and a few small mitochondria. The processes are few and relatively straight when cut in longitudinal section. The predominant cellular type in an oligodendroglioma was similar, with a pale cytoplasm. The astrocytes are variable in appearance. Their nuclei are moderately large, irregularly ovoid, and the cytoplasm adjacent to the nucleus is finely granular and scant. In the protoplasmic astrocytes the cytoplasm has a complicated infolded arrangement with reduplication of the plasma membrane, numerous processes extending radially from the cell and rebranching. To a certain extent this same folded plasma membrane was noted in the fibrous astrocytes. However, their more distant processes were narrowed, relatively straight, and filled with numerous dense fibrils. The processes of the astrocyte often surrounded axons, and other cellular processes, and surrounded some vessels, while attaching to a part of the wall of another vessel. Proliferating cells in experimentally produced gliosis and in astrocytic neoplasms were similar in structure.
The ependymal cells and the epithelium of the choroid plexus have a specialized surface with microvillous projections of the cytoplasm covered by the plasma membrane. Cilia in varying numbers are present in both epithelia.
DEVELOPMENT OF AN IMPROVED MEDIUM FOR THE ISOLATION OF LIVER MITOCHONDRIA
Authors: Birbeck M. S. C. , Reid E. 
Published: May 2004

In view of the unsatisfactory appearance, under the electron microscope, of liver mitochondria isolated in isotonic sucrose medium, alternative media have been examined. It was found to be advantageous to replace sucrose by raffinose, and to add levan or, preferably, dextran, together with heparin in suitable concentration. With the optimal medium, the constituents of which are raffinose, versene (optional), dextran of high molecular weight, heparin, and AMP (optional), most of the mitochondria in the osmium-fixed pellet are apparently intact, and show the membranes characteristic of mitochondria as seen in cell sections.
The optimal medium has no adverse effect on the activity of the several tissue enzymes which have been studied, except that Mg++-activated ATPase is partially inhibited if the medium is present in high concentration in the assay system. Mitochondrial fractions isolated in the new medium have, in common with sucrose fractions, appreciable "free" ATPase activity, this activity being evidently a poor criterion of mitochondrial integrity. Use of the new medium does not decrease the proportion of cytoplasmic ATPase which fails to sediment with the mitochondria, but does give a mitochondrial fraction low in RNA and in acid phosphatase activity and little contaminated with microsomal material. Particles tentatively identified as "lysosomes" have been seen in certain sections.