bluuebunny/crossref_metadata_2025_split huggingface dataset:
A Cytochemical Study of the Stem Cell Concept in Specimens of a Human Ovarian Tumor
Authors: Bader Saul 
Published: May 2004

The amounts of DNA in interphase nuclei were compared with the amounts of DNA in metaphase and anaphase figures in Feulgen-stained tissue sections of 5 specimens of the human ovarian papillary serous adenocarcinoma. The relative amounts of DNA per cell were determined by cytophotometric measurements of interphase nuclei at a single wavelength and of mitotic figures by the two wavelength method.
The 5 specimens conformed to the stem cell concept of cell proliferation since anaphase distributions of amounts of DNA were restricted to a narrow range of DNA values indicating the successful mitosis of a single cell type (stem cell) out of several cell types whose presence were suggested by the wide spread of interphase and metaphase values. In addition, the data indicated that, in some instances, only the amounts of DNA in anaphase figures can reliably identify the stem cell. Changes in the frequency of dividing cells having doubled amounts of DNA, and/or the presence of cells resulting from endoreduplication can distort the interphase distribution of amounts of DNA and thus give rise to a modal DNA interphase value which is not the same as the DNA value of the stem cell (anaphase figures).
Submicroscopic Changes in Visual Cells of the Rabbit Induced by Iodoacetate
Authors: Lasansky Arnaldo , De Robertis Eduardo 
Published: May 2004

Alterations produced by iodoacetate in visual cells have been studied under the electron microscope. Lesions of the outer segments of the rods are visible as early as 3 hours after a single injection of 20 mg. iodoacetate per kg. body weight. After 6 hours the changes are more marked and consist then of disorganization, vesiculation, and lysis of the rod sacs. The inner segments of most rod cells show swelling and vacuolization of the matrix, the endoplasmic reticulum, and the Golgi complex. The mitochondria of the ellipsoid show a tendency to disintegrate. In some inner segments the changes consist primarily in an increase in density of the matrix and deposition of a granular material. The rod synapses are also affected, showing lysis of the synaptic vesicles and alterations of the synaptic membrane.
With a second injection of 20 mg. iodoacetate per kg. body weight, all these changes become more marked and lead to complete destruction of the rod cells.
The cones seem more resistant than the rods. A single injection produces no visible changes in the outer or inner segments of the cones. At cone synapses, however, there are changes consisting of fusion of synaptic vesicles and other membranous material to form large concentric membranes characteristic of myelin figures. A second dose of the drug causes complete destruction of the cone cells.
All these, and other submicroscopic changes, are discussed in relation to various hypotheses put forward to explain the mode of action of iodoacetate on visual cells. The pronounced alterations of submicroscopic intracellular membranes suggest that the locus of action of iodoacetate may be a component widely dispersed throughout the visual cells and related, in some way, to the maintenance of these lipoprotein structures.
Cytophotometric Study of Deoxyribonucleic Acid in Cortisone-Treated Rat Hepatocytes
Authors: Lowe Charles U. , Box Harold , Venkataraman P. R. , Sarkaria D. S. 
Published: May 2004

Rats were treated by intramuscular injection with cortisone acetate, 25 mg./day for 5 days. Small pieces of liver obtained from treated and normal animals were squashed on a microscope slide so as to obtain many areas only a single cell in thickness. After Feulgen staining to demonstrate DNA, optical density was measured using a projection technique.
In both the normal and treated animals the nuclei were easily segregated in three ploidy classes, diploid, tetraploid, and octaploid, depending upon Feulgen intensity. In all three classes, the absorbence of nuclei from cortisone-treated animals was approximately 20 per cent lower than the normal. These data were interpreted to indicate that a change in DNA content had been induced by cortisone administration. These findings are comparable to data obtained from similar animals using chemical methods for the determination of DNA.
C14 Assays and Autoradiographic Studies on the Rooster Comb
Authors: Balazs Endre A. , Szirmai John A. , Bergendahl Gudrun 
Published: May 2004

The distribution of C14 was studied in various parts of the rooster comb following treatment with testosterone. The value of gas-phase assay of C14 in tissue has been demonstrated and the results compared with those of autoradiographic studies on the same tissue.
The results of these experiments showed that androgen treatment significantly increases the rate of incorporation of C14 in various parts of the comb. The specific activity of carbon in the comb, cornea, and liver differed, depending on which precursor, viz. glucose-6-C14, glucose-1-C14, and glucuronolactone-U-C14, was administered. The highest values were obtained after the administration of glucose-6-C14; glucuronolactone-U-C14 gave the lowest specific activity.
The specific activity of carbon in different parts of the comb showed considerable variation. Carbon assay of serial sections of the comb cut at various planes showed that the specific activity of carbon was highest in the mucoid layer. Both C14 assays and autoradiograms indicate that C14 is also present in other parts of the comb. As seen in autoradiography, the concentration of C14 was highest in the epithelium, in the blood vessel walls, and in the avascular collagenous tissue. These results, and indications from previous studies, suggest that the high specific activity of carbon in the mucoid layer is due mainly to the presence of C14-labelled hyaluronic acid. Autoradiograms and PAS staining suggest that a significant amount of C14 is also incorporated into the glycoproteins associated with the collagen fibers.
The Relation between Protein Synthesis and Lipide Accumulation in L Strain Cells and Ehrlich Ascites Cells
Authors: King Donald W. , Socolow Edward L. , Bensch Klaus G. 
Published: May 2004

It has long been known that fat accumulates in old injured cells both in tissue culture and in many mammalian disease states. The use of L cells grown in suspension tissue culture permitted the opportunity to study conditions in which lipide accumulation could be retarded or accelerated.
These cultures exhibit a three-phase growth curve which is similar to that previously found with bacteria and consists of a lag period, logarithmic growth period, and stationary period. Daily aliquots were removed from cultures going through these phases and protein and cholesterol content correlated with cell division.
It was found that L cells gradually accumulated lipide in the cell concurrent with retardation of cell division and protein synthesis. Conversely old lipide-laden cells, placed in fresh media and encouraged to active division with net protein synthesis progressed from a high to a low lipide/cell ratio over a period of 2 to 4 days. An amino acid analogue p-fluorophenylalanine and a mitotic inhibitor, colchicine, also markedly increased the lipide/cell ratio. Similar results were found in in vitro experiments with Ehrlich ascites cells.
The Occurrence of Intercellular Bridges in Groups of Cells Exhibiting Synchronous Differentiation
Authors: Fawcett Don W. , Ito Susumu , Slautterback David 
Published: May 2004

A previous electron microscopic study of the cat testis revealed that spermatids derived from the same spermatogonium are joined together by intercellular bridges. The present paper records the observation of similar connections between spermatocytes and between spermatids in Hydra, fruit-fly, opossum, pigeon, rat, hamster, guinea pig, rabbit, monkey, and man. In view of these findings, it is considered likely that a syncytial relationship within groups of developing male germ cells is of general occurrence and is probably responsible for their synchronous differentiation. When clusters of spermatids, freshly isolated from the germinal epithelium are observed by phase contrast microscopy, the constrictions between the cellular units of the syncytium disappear and the whole group coalesces into a spherical multinucleate mass. The significance of this observation in relation to the occurrence of abnormal spermatozoa in semen and the prevalence of multinucleate giant cells in pathological testes is discussed.
In the ectoderm of Hydra, the clusters of cnidoblasts that arise from proliferation of interstitial cells are also connected by intercellular bridges. The development of nematocysts within these groups of conjoined cells is precisely synchronized.
Both in the testis of vertebrates and the ectoderm of Hydra, a syncytium results from incomplete cytokinesis in the proliferation of relatively undifferentiated cells. The intercellular bridges between daughter cells are formed when the cleavage furrow encounters the spindle remnant and is arrested by it. The subsequent dissolution of the spindle filaments establishes free communication between the cells. The discovery of intercellular bridges in the two unrelated tissues discussed here suggests that a similar syncytial relationship may be found elsewhere in nature where groups of cells of common origin differentiate synchronously.
The Metabolism of Chromosomal Ribonucleic Acid in Drosophila Salivary Glands and its Relation to Synthesis of Desoxyribonucleic Acid
Authors: McMaster-Kaye Rachel , Taylor J. Herbert 
Published: May 2004

Incorporation of adenine-8-C14 into chromosomal nucleic acids of Drosophila salivary glands has been observed with the autoradiographic technique. RNA-C14 and DNA-C14 were detected as the fractions extractable by ribonuclease digestion and resistant to ribonuclease, respectively. Extractions with desoxyribonuclease and acids were also used to identify the nucleic acids.
Time-course curves were determined from grain counts. RNA-C14 concentration reached a maximum in 2 hours, and decreased after the 4th hour. DNA-C14 concentration reached its maximum within 8 hours, and showed no decreases during a 48-hour experiment.
In the latter part of the period of observation, morphological differentiation of the gland occurred, the decrease in RNA-C14 became very rapid, and a large increase in DNA-C14 was observed. Marked decrease in RNA-C14 and increase in DNA-C14 were detectable in a few hours when isotope was administered shortly before visible differentiation of the gland.
Measurements of nuclear size indicated no significant decreases in RNA-C14 amount prior to the period of differentiation. During this later period, a large decrease in RNA-C14 amount occurs suddenly, and the same amount of C14 is added simultaneously to the DNA fraction, as expected if RNA-C14 is utilized in the synthesis of DNA.
The Endoplasmic Reticulum and the Golgi Structures in Maize Root Cells
Authors: Whaley W. Gordon , Mollenhauer Hilton H. , Kephart Joyce E. 
Published: May 2004

Maize root tips were fixed in potassium permanganate, embedded in epoxy resin, sectioned to show silver interference color, and studied with the electron microscope. All the cells were seen to contain an endoplasmic reticulum and apparently independent Golgi structures.
The endoplasmic reticulum is demonstrated as a membrane-bounded, vesicular structure comparable in many aspects to that of several types of animal cells. With the treatment used here the membranes appear smooth surfaced. The endoplasmic reticulum is continuous with the nuclear envelope and, by contact at least, with structures passing through the cell wall. The nuclear envelope is characterized by discontinuities, as previously reported for animal cells. The reticula of adjacent cells seem to be in contact at or through the plasmodesmata. Because of these contacts the endoplasmic reticulum of a given cell appears to be part of an intercellular system.
The Golgi structures appear as stacks of platelet-vesicles which apparently may, under certain conditions, produce small vesicles around their edges. Their form changes markedly with development of the cell.
ELECTRON MICROSCOPE RADIOAUTOGRAPHIC IDENTIFICATION OF SEROTONIN-SYNTHESIZING CELLS IN THE MOUSE GASTRIC MUCOSA
Authors: Rubin Walter , Gershon Michael D. , Ross Leonard L. 
Published: May 2004

This study correlates the fine structure of mouse gastric endocrine cells with their ability to synthesize serotonin (5-HT) from 5-hydroxytryptophan (5-HTP). Mice were sacrificed 2 hr after the intravenous injection of 5-HTP-3H or 5-HT-3H. Their stomachs were processed for light- and electron microscope radioautography in a manner which retained labeled 5-HT while washing out other labeled substances. Stomachs from additional mice were incubated in vitro with 5-HT-3H and processed similarly.
All morphologic types of mouse gastric endocrine cells exhibited a similar facility to incorporate exogenous 5-HTP and to convert it to 5-HT which was bound intracellularly. Differences in densities of silver grains observed over endocrine cells suggested that individual endocrine cells indeed varied in their ability to synthesize and/or to bind 5-HT; such variations, however, were not reflected by differences in fine structure, with the exception that endocrine cells with few granules always contained little newly synthesized 5-HT. The newly synthesized 5-HT was associated with the intracellular granules. The gastric endocrine cells were not labeled by exogenous 5-HT-3H, whereas mast cells were labeled by either 5-HT-3H or 5-HTP-3H administration. The findings of the present study support the position that the gastric endocrine cells represent a single cell type, at least in respect to serotonin metabolism—that the argyrophil or argentaffin reactivity of these cells merely reflects their amine content at a given time.
LOCALIZATION AND PROPERTIES OF THE CHOLINESTERASE IN CRUSTACEAN MUSCLE
Authors: Spielholz Neil I. , Van der Kloot William G. 
Published: May 2004

Cholinesterase (ChE) activity is present in crustacean muscle extracts. However, since acetylcholine (ACh) is not a neuromuscular transmitter in these animals, the role and exact localization of ChE was unknown.
The histochemical localization of the enzyme was studied in whole muscle and in the sarcoplasmic reticulum fraction of the extract, 50-µm frozen sections of glutaraldehyde-fixed crayfish tail flexor muscle were incubated with acetylthiocholine (ATC) as substrate, and examined under the electron microscope. After some modifications in published techniques, dense deposits were found associated with the sarcolemma, sarcolemmal invaginations, and transverse tubules. No deposits were found in 10-4 M eserine, or if butyrylthiocholine (BTC) was substituted for ATC. The vesicles in the sarcoplasmic reticulum fraction which demonstrate the activity must represent minced bits of these membranes.
Using a spectrophotometric method, the kinetics of the crustacean muscle enzyme was compared to the acetylcholinesterase (AChE) on mammalian red blood cells and in the lobster ventral nerve cord. Surprisingly, and contrary to previous reports, the crustacean muscle enzyme did not demonstrate substrate inhibition. While a number of similarities to AChE were found, this lack of substrate inhibition makes questionable an unequivocal similarity with classical AChE.
A SCANNING ELECTRON MICROSCOPE STUDY OF SURFACE FEATURES OF VIRAL AND SPONTANEOUS TRANSFORMANTS OF MOUSE BALB/3T3 CELLS
Authors: Porter Keith R. , Todaro George J. , Fonte Virginia 
Published: May 2004

Cells of the mouse line Balb/3T3 as well as three virus-induced transformants and two spontaneous transformants grown in vitro have been studied for their topography by scanning electron microscopy. The parent cell in confluent culture closely resembles an endothelial cell in its form and in the structure of its association with adjacent cells. The tumorigenic transformants produced by SV40, murine sarcoma virus, or polyoma viruses are fusiform to pleomorphic and distinctly different from the cell of origin. They show relatively smooth surfaces except for blebs and marginal microvilli. Perhaps most surprising is the similarity they bear to one another. This is made the more singular by the very different form shown by the tumorigenic transformants of spontaneous origin. One of these, S2-4, possesses a thickened rather than the lamellar form of the parent A31 cell and is covered by long microvilli and many spherical blebs. The other, TuT3, more closely resembles the cell of origin but shows extensive ruffling at its margins. All transformants grow without evidence of contact inhibition.
The significance of the surface morphologies and the factors influencing cell form are discussed.
PRODUCTION AND RELEASE OF A LOCUS-SPECIFIC RIBONUCLEOPROTEIN PRODUCT IN POLYTENE NUCLEI OF DROSOPHILA HYDEI
Authors: Derksen J. , Berendes H. D. , Willart E. 
Published: May 2004

A specific, 0.1–0.3-µm large ribonucleoprotein complex consisting of a central core with stalklike extensions on top of which 280–320-Å ribonucleoprotein particles are situated is found in an experimentally activated chromosome region, 2–48C, of the polytene chromosomes of Drosophila hydei. Alkaline hydrolysis, RNAse digestion, and uranyl-EDTA-lead staining indicated the ribonucleoprotein character of the 280–320-Å particles, whereas the central core seems to be devoid of RNA.
The characteristic complexes are present in the nucleoplasm and at the nuclear membrane, but absent from the cytoplasm. It is suggested that the large RNP complexes are the specific products of the puff at 2–48C. Complexes similar to the ones described have not been observed in any other region of the polytene salivary gland chromosomes of this species.
Nuclear-Cytoplasmic Relationships in Human Cells in Tissue Culture
Authors: Goldstein Lester , Micou Julie 
Published: May 2004

The movement of ribonucleic acid (RNA) from nucleus to cytoplasm has been studied, by autoradiographic techniques, in cells of the human amnion grown in tissue culture.
Cells were exposed to cytidine-H3 for 1 hour after which time only the RNA of the nuclei was labelled. After this 1 hour exposure the cells were placed in a medium containing an excess amount of unlabelled cytidine. Periodically, cells from this medium were fixed. Autoradiographs showed that there was a progressive movement of the label from nucleus to cytoplasm, such that after 24 hours essentially all the label was in the RNA of the cytoplasm.
A study of the incorporation of the cytidine-H3 in deoxyribonucleic acid (DNA), in the same population of cells at the same times, indicated that the presence of excess amounts of unlabelled cytidine almost instantaneously inhibited further utilization of cytidine-H3.
It is concluded that RNA moves from nucleus to cytoplasm as a complex polynucleotide structure.
Electron Microscope Observations of the Melanocyte of the Human Epidermis
Authors: Charles Arwyn , Ingram John T. 
Published: May 2004

Using standard osmium fixation and methacrylate embedding techniques, a study has been made of the melanocyte of human biopsy skin removed under general and local anaesthesia. Melanogenesis was easily observable in the melanocytes, but immature pigment granules were rarely seen in the Malpighian cells. The passage of melanin from melanocyte to Malpighian cell—cytocrine secretion—is thought to have been observed. Phagocytes near the dermal-epidermal junction seem to have their pigment granules in vacuoles, rather than surrounded directly by the cytoplasmic matrix as in the melanocytes. This, together with the failure to observe "effete" melanocytes, prompts the suggestion that the phagocytes are melanocytes which have migrated from the epidermis into the dermis.
A melanin granule is shown with alternating dark and lighter transverse striations, concerning which structure little can at present be said.
Histochemical and Autoradiographic Studies on the Effects of Aging on the Mucopolysaccharides of the Periosteum
Authors: Tonna Edgar A. , Cronkite Eugene P. 
Published: May 2004

An autoradiographic study was made using S35-sulfate for the localization, distribution, and variation in the mucopolysaccharide content of the femoral periosteum of rats from birth to old age. The mucopolysaccharides were also studied histochemically, using toluidine blue O, Rinehart and Abu'l-Haj's colloidal iron method, and the periodic acid-Schiff reaction, before and after hyaluronidase treatment.
Autoradiograms revealed the uptake of S35 particularly in the vicinity of the preosseous zone and adjacent osteoblasts. This labelling was highest at the period of rapid bone growth. With increasing age, the S35 uptake became progressively less. The preosseous zone showed γ-metachromatic staining at all ages after treatment with toluidine blue. Active osteoblasts were mostly orthochromatic, however, ß-metachromasia was exhibited at a later age. Abundant amounts of intra- and extracellular mucopolysaccharides of both the acid and neutral type were demonstrated in the periosteum.
S35 uptake and γ-metachromasia show the presence of sulfated mucopolysaccharides, of which chondroitin sulfate predominates in the preosseous zone. Since S35 uptake is high in active osteoblasts, the inability to demonstrate metachromasia in osteoblasts may indicate either that chondroitin sulfate is liberated as fast as it is being produced, or that it may be present within the cells in a precursor form not detectable by histochemical methods.
Differents aspects du fer dans l'organisme
Authors: Bessis Marcel , Breton-Gorius Janine 
Published: May 2004

On voit des molécules de ferritine apparaitre dans le cytoplasme des cellules réticulaires au cours de la digestion des érythrocytes, autour des stromas phagocytés.
Cette ferritine s'accumule en amas dans lesquels entrent d'autres substances, en particulier des lipides, provenant aussi des stromas globulaires et qui apparaissent sous forme myélinique.
Souvent la ferritine se dispose d'une manière cristalline. Parfois la ferritine et l'apoferritine alternent dans ces cristaux. Parfois l'hémosidérine contient des cristaux qui semblent bien être de l'apoferritine pure.
L'injection de sels de fer donne lieu à l'apparition de ferritine dans les cellules réticulaires. Dans les conditions de nos expériences, la plus grande partie du fer injecté était sous forme de ferritine dans un délai de 3 jours. Un aspect intermédiaire entre celui du fer injecté et celui de la ferritine a été trouvé. Dans le cas des injections de saccharate de fer ce sont de fines aiguilles; dans le cas des injections de lactate de fer, il s'agit de masses fibreuses.
The Structure of the Mitochondrial Membrane: Inferences from Permeability Properties
Authors: Tedeschi Henry 
Published: May 2004

Mitochondria possess a semipermeable membrane with properties similar to the cell membrane. Despite the presence of a limiting membrane, mitochondria swell approximately 4 to 5 times their original volume without lysis or loss of internal solute. For this reason, it has been argued that the membrane might be convoluted. The present kinetic study of the permeability of isolated mitochondria was undertaken to clarify this question. A photometric method described previously was used.
In the case of highly lipid soluble penetrants, the results suggest that neither the permeability nor the surface area available for penetration varies significantly during considerable swelling. These results may be interpreted to mean that the mitochondrial membrane is convoluted. For highly polar compounds, the permeability of the membrane also remains unchanged during swelling, but the surface area available to penetration increases. These results may be interpreted to mean that in this latter case, the surface of the convolutions becomes available only after they are unfolded by swelling.
The simplest model that can explain the permeability properties of this membrane consists of a bimolecular lipid layer where the inner monomolecular layer is convoluted.