bluuebunny/crossref_metadata_2025 huggingface dataset:
THE FINE STRUCTURE OF CAPILLARIES AND SMALL ARTERIES
Authors: Moore Dan H. , Ruska Helmut
Published: May 2004

Details of capillary endothelia of the mammalian heart are described and compared with capillaries of other organs and tissues. Continuous invagination and pinching off of the plasma membrane to form small vesicles which move across the cytoplasm are suggested as constituting a means of active and selective transmission through capillary walls (12). This might be designated as cytopempsis (transmission by cell).

The fine structure of the different layers in the walls of small heart arteries is demonstrated. Endothelial protrusions extend through windows of the elestica interna to make direct contact with smooth muscle plasma membranes. The elastica interna appears to vary greatly in both thickness and density, and probably restricts filtration, diffusion, and osmosis to such an extent that windows and the transport mechanisms described (cytopempsis) are necessary for the functional integrity of the smooth muscle layer. The contractile material consists of very fine, poorly oriented filaments.
FEULGEN NUCLEAL REACTION
Authors: Hiraoka Tosisuke
Published: May 2004

A new extraction method for the quantitative determination of the fuchsin contained in a Feulgen-stained nucleoprotein sample has been introduced. The method is based on the following facts: (1) Treatment of a Feulgen-stained nucleoprotein sample with hot acid or alkali brings about a splitting of the linkage between fuchsin-SO2 and the hydrolyzed nucleic acid moiety of nucleoprotein through aldehyde groups. (2) It also effectuates the formation of fuchsin from the liberated fuchsin-SO2. (3) The fuchsin is made colorless by the treatment, but is restored to its original pink colored state when the pH of the acidic or alkaline medium is adjusted to 4.6. (4) The fuchsin, either pink colored or decolorized by alkali, can be extracted from an aqueous phase by amyl alcohol. A linear relationship was found to exist between the amount of fuchsin extracted by the FEM from a Feulgen-stained nucleoprotein sample and its DNA content. This relationship holds over a wide range of DNA concentration. From experiments utilizing this method, knowledge may be gained about the mechanism of the Feulgen reaction in situ which can lead to an improvement of the reaction in the field of cytochemistry.
THE SOLUBILITY AND PROPERTIES OF A PURIFIED ICHTHYOCOL IN SALT SOLUTIONS OF NEUTRAL pH
Authors: Gallop Paul M. , Seifter Sam , Meilman Edward
Published: May 2004

1. Purified citrate-extracted ichthyocol obtained from carp swim bladders has been further characterized with respect to its content of certain amino acids and carbohydrate substances.

2. The degree of solubilization or dispersion of ichthyocol by solutions of certain salts maintained in the range of neutral pH and at a temperature of 0–2°C. has been determined.

3. While a number of salts of monovalent cations had no significant solubilizing effects on ichthyocol, ammonium chloride in a concentration of 1 M did cause solution of the protein.

4. Sodium thiosulfate in a range of concentrations caused the solubilization of ichthyocol but was most effective in an intermediate concentration of 0.25 M.

5. Several salts of divalent cations, in particular the chlorides of calcium, magnesium, and barium, and magnesium thiosulfate in concentrations ranging from 0.3 to 1 M caused the immediate and complete solubilization of the ichthyocol.

6. Solutions of ichthyocol in calcium chloride, magnesium chloride, and sodium thiosulfate buffered or adjusted to pH 7.0, were studied with respect to intrinsic viscosity of the protein, optical rotation, ultracentrifugal sedimentation, and reconstitution into fibers. It was found in each case that the original characteristics of the collagen, as determined previously in acid solution, were maintained when the protein was dissolved in salt solutions of neutral pH. No evidence of denaturation or gelatinization could be found when ichthyocol was solubilized under the stated conditions.

7. Collagen in neutral solution with sodium thiosulfate, calcium chloride, or magnesium chloride was not attacked by trypsin as determined viscometrically at 20.0°C., but was rapidly degraded by a purified bacterial collagenase.
THE EFFECTS OF FLUORIDE FEEDING ON THE ORGANIC MATRIX OF BONES AND TEETH OF PIGS AS OBSERVED BY AUTORADIOGRAPHY AFTER IN VITRO UPTAKE OF CA45 AND S35
Authors: Bélanger L. F. , Visek W. J. , Lotz W. E. , Comar C. L.
Published: May 2004

Demineralized sections of fluorinated bones and teeth have been studied by autoradiography following in vitro uptake of Ca45 or S35O4.

The portions of tissue which do not become mineralized (cartilage, prebone, predentine, and precementum) show an increased Ca45 uptake apparently related to an increase in chondroitin sulfate content in fluorosis.

The tissues from the fluoride-fed animals show an increase of in vitro uptake of sulfur in the tissues which become mineralized (bone, dentine, cementum).
HISTOCHEMICAL DEMONSTRATION OF THE SITES OF ACTIVITY OF DEHYDROGENASE SYSTEMS WITH THE ELECTRON MICROSCOPE
Authors: Barrnett Russell J. , Palade George E.
Published: May 2004

In the present study a histochemical method demonstrating the activity of dehydrogenase systems was developed for electron microscopy, utilizing potassium tellurite as the hydrogen or electron acceptor. This reagent was used intravitally (intravenously, intraperitoneally, or intraluminally in hollow organs) or supravitally on small blocks of tissue for the demonstration of endogenous dehydrogenase activity. Blocks of tissue which had been frozen and thawed or which had been washed in 0.44 M sucrose to prevent endogenous activity, were used to demonstrate the activity of the succinic dehydrogenase system. In the latter case, the incubating medium contained tellurite, succinate, phosphate buffer, sucrose, and activators. The incubation was as performed either aerobically (with or without the addition of potassium cyanide) or anaerobically. The specificity and the enzymatic nature of the reactions were ascertained by appropriate control experiments.

Reduced tellurite, the end product of this histochemical reaction, could be visualized in thin sections of osmium tetroxide-fixed, methacrylate-embedded tissues as crystals or fine particulate deposits of high density, localized on, or in close relationship to mitochondrial membranes. The results of these experiments are demonstrated, utilizing heart muscle (rat) as the source of the enzyme systems.
ELECTRON MICROSCOPE STUDIES OF THE FORMATION OF NODES OF RANVIER IN MOUSE SCIATIC NERVES
Authors: Uzman Betty Geren , Nogueira-Graf Genevieve
Published: May 2004

Observations with the electron microscope of longitudinal sections of the sciatic nerves of infant mice during the period of early myelin formation are described.

These observations are interpreted in relation to previous studies of transverse sections, and a general picture of the formation of an internodal length of the myelin sheath in three dimensions is formulated.

In general, an internodal length of myelin sheath is attained by the spiral wrapping of the infolded Schwann cell surface; the increase in length of the internode during maturation is at least partially explained by the increased length of axon covered by the overlapping of successive layers during the wrapping of the infolded Schwann cell surface; and the nodes of Ranvier refer to the structure complex at the junctions of adjacent non-syncytial Schwann cells. The fact that the mode of formation of myelin brings each of its layers into intimate contact with the axon surface at the nodes is emphasized because of the possible functional significance of this arrangement. The manner of origin of Schmidt-Lantermann clefts remains obscure.

Certain isolated observations provide evidence for the possibility that occasional internodes of myelin may form from several small segments of myelin within a single Schwann cell.
Cytoplasmic Incorporation of a Ribonucleic Acid Precursor in Amoeba proteus
Authors: Plaut Walter , Rustad Ronald C.
Published: May 2004

The question of RNA synthesis in enucleate cytoplasm of Amoeba has been approached experimentally by incubating enucleate amoebae in a labelled RNA precursor and determining the incorporation into RNA autoradiographically. The results indicate that there is a cytoplasmic incorporation mechanism which can operate in the absence of the nucleus. A comparison is made between Acetabularia and Amoeba with respect to the origins of cytoplasmic RNA. It is concluded that the existing data are consistent with the assumption that some cytoplasmic RNA is of nuclear origin in both organisms.
THE DOUBLE ARRAY OF FILAMENTS IN CROSS-STRIATED MUSCLE
Authors: Huxley H. E.
Published: May 2004

The conditions under which one might expect to see the secondary filaments (if they exist) in longitudinal sections of striated muscle, are discussed. It is shown that these conditions were not satisfied in previously published works for the sections were too thick. When suitably thin sections are examined, the secondary filaments can be seen perfectly easily. It is also possible to see clearly other details of the structure, notably the cross-bridges between primary and secondary filaments, and the tapering of the primary filaments at their ends. The arrangement of the filaments and the changes associated with contraction and with stretch are identical to those already deduced from previous observations and described in terms of the interdigitating filament model in previous papers. There are therefore excellent grounds for believing that this model is correct. The alternative models which have been proposed appear to be incompatible both with the present observations and with much of the other available evidence.
THE CRYSTAL STRUCTURE OF α-CHITIN (POLY-N-ACETYL-D-GLUCOSAMINE)
Authors: Carlström Diego
Published: May 2004

A detailed model for the crystal structure of the fibrous polysaccharide chitin is proposed. The structure determination has been carried out by using an optical analogue instrument which proved to be an adequate and rapid tool for the derivation of Fourier transforms, signs of amplitudes and the production of optical Fourier syntheses. The new model of chitin accounts properly for known chemical and physical properties, including the infrared absorption as well as for x-ray data, but because of the limited resolution of the diffraction patterns it can only be regarded as a good approximation. The stereochemical configuration of the polysaccharide chains has certain implications for the structure of cellulose.
ELECTRON MICROSCOPY OF HELA CELLS AFTER THE INGESTION OF COLLOIDAL GOLD
Authors: Harford Carl G. , Hamlin Alice , Parker Esther
Published: May 2004

Tissue cultures of HeLa cells were grown in media containing colloidal gold, and after various intervals, the cells were fixed, embedded, and sectioned for electron microscopy. Uncoated grids with small holes were used in many of the experiments.

Intracellular particles of gold were identified in areas surrounded by single membranes, in moderately dense granules, in globoid bodies, and in the cytoplasmic matrix. Gold particles were not found in typical mitochondria, Golgi complex, ergastoplasm (granular forms of endoplasmic reticulum), or nuclei.

The phenomenon of pinocytosis was considered to be the most likely means by which the gold particles were ingested, and the locations of gold particles appeared to have significance concerning theories that membranous organelles of the cytoplasm may be derived from the cell membrane.
AUTORADIOGRAPHIC DETERMINATION OF S35 IN TISSUES AFTER INJECTION OF METHIONINE-S35 AND SODIUM SULFATE-S35
Authors: Edwards Leon C. , Udupa K. N.
Published: May 2004

The loss of "bound" S35 that occurs during various mounting procedures used in autoradiography was studied in healing surface wounds of rats treated with either methionine-S35 or Na2S35O4. Valid autoradiography of bound S35 in this tissue is not possible until 48 hours after radiosulfate and 24 hours after radiomethionine injection, when the S35 is almost entirely bound in large protein and polysaccharide molecules.

Autoradiograms of S35 given in both the organic and inorganic form reveal substantial over-all loss of the bound isotope from sections subjected to contact with solvents prior to autoradiography. A comparison of autoradiograms prepared by dry-mounting sections of frozen-dried tissue with autoradiograms of wet-mounted sections of the same tissue suggest that the loss is proportional to the extent of the contact with solvents. Evidence suggests that loss of the isotope occurs during contact of the ribbon or section itself with solutions after fixation and cutting and prior to radiation exposure. No appreciable loss of the bound isotope seems to occur during contact of the intact tissue specimen with a variety of fluid fixatives except for a marginal zone at the excision edges of the tissue. The potential hazard of displacement of the isotope during fixation, however, remains.

Technics which prevent loss of the isotope and fogging of the nuclear emulsion permit the use of thinner sections and emulsion films and the fine resolution of image rendered possible by the physical properties of S35.
The Chemical Fractionation of Rabbit and Swine Thymus
Authors: Hess Eugene L. , Lagg Saima E.
Published: May 2004

A chemical fractionation procedure, previously found applicable to bovine thymus and bovine and ovine palatine tonsils, was used to fractionate rabbit and hog thymus. With respect to the chemical fractionation steps, yields of fractions, and optical and electrophoretic properties, extracts from hog and rabbit thymus were indistinguishable from similar extracts prepared from calf thymus. The study provides composition and yield data applicable to the thymus of a small mammal readily available in most laboratories.
ELECTRON MICROSCOPIC OBSERVATIONS OF AMOEBA PROTEUS IN GROWTH AND INANITION
Authors: Cohen Adolph I.
Published: May 2004

Electron microscopic observations have been made on growing and dividing specimens of Amoeba proteus and also on starving animals. Structures presumably corresponding to the mitochondria, alpha particles, vacuoles, and Golgi material are described. A new entity, designated as a foamy particle, is noted.

Descriptions are given of the cytoplasmic and nuclear membranes. During division the inner, thick nuclear membrane component is seen to vanish and the outer membrane persist. Measurements suggest a gradual reappearance of the inner component with growth.

Starving animals show a loss of cytoplasmic granularity and an increase in the electron density of mitochondria, presumably due to lipide accumulation.
CHANGES IN "DROPLET" FRACTIONS FROM RAT KIDNEY CELLS AFTER INTRAPERITONEAL INJECTION OF EGG WHITE
Authors: Straus Werner
Published: May 2004

1. Kidney homogenates from rats injected with egg white and from control rats were fractionated simultaneously into six fractions and the content of acid phosphatase, ribonuclease, desoxyribonuclease, cathepsin, and ß-glucuronidase in corresponding fractions from treated and untreated animals was compared. These observations were correlated with the amount of dark brown bottom sediments in fractions NDrI, DrII, and DrIII, and with the number of droplets in fraction NDrI.

2. It was found that after injection of egg white the amount of small droplets decreased as indicated by the decrease of the dark brown bottom layer in the sediment of fraction DrIII and by the concomitant decrease of hydrolytic enzymes in the same fraction, and that the number of large droplets increased as indicated by the increase of brown sediment in fraction NDrI and the increase in the number of droplets counted in a bacterial counting chamber in the same fraction. It was concluded that the treatment with egg white induced the transformation of small droplets into large droplets.

3. The decrease of hydrolytic enzymes in the fractions containing the small droplets was accompanied by a marked increase of these enzymes in the supernatant fluid. The enzyme content of fraction NDrI was not increased after treatment, although it contained greatly increased numbers of large droplets. Counting of the droplets in this fraction showed decreased enzymatic activity of the average large droplet after treatment with egg white. It was suggested that during the transformation of small into large droplets, a portion of the hydrolytic enzymes was released into the surrounding cytoplasm, and that this was partly responsible for the increased enzyme content of the supernatant fluid after fractionation of the kidney homogenate. In contrast to the four other hydrolytic enzymes, ß-glucuronidase was not increased in the supernatant fluid.

4. Eighteen hours after intraperitoneal injection of egg white, the specific enzymatic activities of kidney homogenates showed a 25 to 35 per cent increase for cathepsin, ribonuclease, and desoxyribonuclease, no change for acid phosphatase and ß-glucuronidase, and approximately a 7 per cent decrease for cytochrome oxidase. The increase of cathepsin, ribonuclease, and desoxyribonuclease in the total homogenate was interpreted as an indication of the formation of new enzymes, and it was suggested that this partly accounted for the increase of these enzymes in the supernatant fluid.

5. The activation of the enzymes by osmotic effects was investigated in vitro by incubation of droplet fractions in the presence of different concentrations of sucrose.
MICROSPECTROPHOTOMETRY OF CELL NUCLEI STAINED WITH THE FEULGEN REACTION
Authors: Naora Hiroto
Published: May 2004

1. DNA contents of the individual parenchymal nuclei of rat livers during postnatal growth were estimated by microspectrophotometric apparatus, and different ploidy classes of nuclei were classified by their DNA contents. With the same material the total number of parenchymal nuclei in the liver was counted microscopically.

2. If the DNA content of nuclei encountered most frequently in several tissues represents the diploid class, the ploidy classes of the rat liver cell nuclei correspond to di-, tri-, tetra-, and octoploid, with the di- and tetraploid ones predominating considerably.

3. In suckling rats (below 25 gm. of body weight) the liver parenchyma is composed almost exclusively of cells with diploid nuclei, whereas in young rats (above 80 gm.), of tetraploid nuclei. In the growth stage between 25 and 80 gm., there is a remarkable replacement of the diploid nuclei by the tetraploid ones. However, in the liver of adult rats weighing more than 150 gm., any increase or decrease in the frequency of diploid and tetraploid nuclei is hardly observable. In such rats, the nuclear population of the liver parenchyma seems to reach a cell-ecological equilibrium which is considered to be a stable one.

4. It is shown that such nuclear populations and the total number of nuclei in a liver are controlled by the growth state, and not by the age.

5. The decrease in the total number of diploid nuclei and the increase in tetraploid nuclei in the growing livers of rats weighing from 40 up to 130 gm. can both be explained by the hypothesis that the tetraploid nuclei originate from the interphase diploid nuclei without involving mitosis. This hypothesis implies that mitosis is confined to the reproduction of diploid cells alone.

6. It is suggested that, in general, the synthesis of DNA does not necessarily result in the formation of visible mitotic chromosomes.

7. Mitotic time and generation time of diploid nuclei and the percentage of the tetraploidization from diploid nuclei are calculated and discussed.
PHYSICAL STUDIES OF PHOSPHOLIPIDS
Authors: Chapman D. , Fluck D. J.
Published: May 2004

On heating pure, fully saturated 2,3-diacyl-DL-phosphatidyl-ethanolamines and 2,3-diacylphosphatidyl-cholines (lecithins) in water to the transition temperature at which large endothermic heat changes occur, they are observed, by light microscopy, to form myelin figures. This result is discussed in terms of the large difference in the transition temperature for "melting" of the hydrocarbon chains of unsaturated and saturated phospholipids and is illustrated by means of differential thermal analysis (D.T.A.) curves. These structures have been examined by electron microscopy after negative staining and after reaction with osmium tetroxide. Typical phospholipid lamella structures are seen in the phosphatidylcholines after negative staining, and in the phosphatidyl-ethanolamines after both negative staining and osmium fixation. The distances across these lamellae have been measured. Some preliminary investigations of the nature of the osmium tetroxide reaction with the phosphatidyl-ethanolamines have been made.
PUROMYCIN-INDUCED NECROSIS OF CRYPT CELLS OF THE SMALL INTESTINE OF MOUSE
Authors: Estensen Richard D. , Baserga Renato
Published: May 2004

Chemical and radioautographic analysis of the small intestine of mice injected intraperitoneally with puromycin revealed an immediate decrease of precursor incorporation into DNA and protein and a delayed decrease of precursor incorporation into RNA. In addition to this decrease of precursor incorporation, damage to the crypt cells, but not to the cells of the villus of the small intestine, was observed. Further examination of other dividing cells (spleen) and nondividing cells (liver and heart) of these mice showed again that only cells of actively dividing tissues were damaged. The metabolic inhibitors actinomycin D, cytosine arabinoside, actidione, and puromycin aminonucleoside were used in an attempt to clarify the mechanism of cell damage by puromycin. The results showed that there was no clear correlation between cell necrosis and the pattern of inhibition of synthesis of DNA, RNA, or protein.
RADIOAUTOGRAPHIC COMPARISON OF THE UPTAKE OF GALACTOSE-H3 AND GLUCOSE-H3 IN THE GOLGI REGION OF VARIOUS CELLS SECRETING GLYCOPROTEINS OR MUCOPOLYSACCHARIDES
Authors: Neutra Marian , Leblond C. P.
Published: May 2004

The radioautographic distribution of the label of galactose-H3 was compared with that of glucose-H3 in a series of secretory cells of the rat. Whereas the glucose label appeared in all mucous cells, the galactose label was incorporated only into certain mucous cells. Whenever either label was incorporated, however, it was located first in the Golgi region and later in the secretion product, mucus. Several lines of evidence, including extraction of glucose label with peracetic acid—beta glucuronidase, indicated that the material synthesized in the Golgi region was glycoprotein in nature. In chondrocytes, both the galactose and the glucose label appeared first in the Golgi region and later in cartilage matrix; extraction of glucose label with hyaluronidase indicated that much of it consisted of mucopolysaccharide. In all secretory cells, the extraction of glycogen by amylase had no effect on Golgi radioactivity. Such extraction did not eliminate the scattered cytoplasmic label also seen after glucose-H3 injection, but completely eliminated that seen after galactose-H3. Consequently, the galactose-H3 label in the Golgi region stood out more clearly, and was detected in many cells: pancreas, liver, epididymis, and intestinal columnar cells. In the latter, label later appeared in the surface coat. Thus, radioautography after injection of galactose-H3, as after glucose-H3, indicates that synthesis of complex carbohydrates takes place in the Golgi region of many secretory cells.
STUDIES ON CELL DEFORMABILITY
Authors: Weiss Leonard
Published: May 2004

Murine sarcoma 37 ascites cells were treated with the proteolytic enzymes, trypsin and chymotrypsin, after which cellular deformability and electrophoretic mobility were measured. It was shown that incubation with trypsin increased the ease with which the cells could be deformed without changing electrophoretic mobility, and that diisopropylfluorophosphate (DFP)-trypsin was inactive, a fact which suggests that trypsin-sensitive peptide linkages help to maintain the "tension" at the cell periphery. On the other hand, chymotrypsin reduced cellular electrophoretic mobility without appreciably altering deformability. This suggests that, although chymotrypsin-sensitive bonds do not contribute to "tension," they are in some way associated with charged groups at the cell periphery.
OBSERVATIONS ON SPERMIOGENESIS IN THE FUNGUS GNAT SCIARA COPROPHILA
Authors: Phillips David M.
Published: May 2004

Although 9-membered centrioles are found in somatic tissues of Sciara, the centriole which lies at the spindle pole of the second meiotic division in male Sciara is composed of a row of approximately 70 short tubules in an oval array. Shortly after telophase of this unequal division, in the daughter cell destined to undergo spermiogenesis, microtubules become confluent with the tubules of the centriole. These tubules have the same density as other cytoplasmic microtubules after glutaraldehyde-OsO4 fixation and, like them, are not preserved with OsO4 fixation. As the centriole, now with approximately 70 attached, posteriorly directed, doublet tubules, migrates from the polar to the apolar end of the nucleus to take a final position in an oval groove which forms in the nuclear envelope, the tubules lengthen and become demonstrable after OsO4 fixation and more electron opaque than other cytoplasmic microtubules following glutaraldehyde-OsO4 fixation. Later, a singlet tubule appears peripherally to each doublet of the oval and 4 "arms" develop at specific sites on the tubules. Posteriorly, where the oval of tubules becomes discontinuous and forms a spiral, the arrangement of arms is different and the singlet tubules are lacking. Dense solid bodies develop inside this odd flagellum and become enclosed by a smooth double membrane. A single mitochondrial derivative has three components: a central area of homogeneous, moderately electron-opaque, proteinaceous material; a peripheral ring of cristae; and a crystalloid which is specifically oriented with respect to the flagellar tubules.
CULTIVATION OF MAMMALIAN CELLS IN DEFINED MEDIA WITH PROTEIN AND NONPROTEIN SUPPLEMENTS
Authors: Healy George M. , Parker Raymond C.
Published: May 2004

An improved chemically defined basal medium (CMRL-1415) has been used to advantage in studying the effects on trypsinized, newly explanted mouse embryo cells of certain glycoproteins from plasma and serum, certain nonprotein macromolecules, and various combinations of these, in stationary cultures. When protein and nonprotein fractions were separated from fetal calf serum, the entire growth activity was found to be associated with the protein. When 100 mg % of dialyzed, freeze-dried, supernatant solution of Cohn's fraction V (method 6) from human plasma was used as a supplement for CMRL-1415, there was considerable improvement in the cultures; and seromucoid prepared from calf serum had a similar effect. Supernatant V was further fractionated by gel filtration to give a threefold concentration of growth activity in a single, highly purified α1-acid glycoprotein (orosomucoid). Starch gel electrophoresis of horse serum that was used to supplement the basal medium revealed a decrease of both α1-acid glycoprotein and α2-macroglobulin during the cultivation of mouse embryo cells. When horse serum was fractionated on DEAE-cellulose columns, the only fraction that showed growth activity was a slow α2-globulin. When the α2-macroglobulin of Schultze was prepared from horse serum by salt precipitation, it was equally effective. When the α2-macroglobulin from horse serum was tested (at 100 mg %) in combination with α1-acid glycoprotein from Supernatant V, seromucoid from calf serum, or unfractionated Supernatant V, the growth response was greatly in excess of that produced by any of these supplements tested separately. The α2-macroglobulin from horse serum could be replaced by certain nonprotein macromolecules (e.g., dextran or Ficoll). Thus, dextran (mol. wt. 100,000 to 200,000) had no visible effect on the cells when used alone at 0.1 or 1%. But when these levels of dextran were used in combination with low molecular weight glycoproteins (e.g., unfractionated Supernatant V at 100 mg %), the cultures remained active and healthy for unusually long periods.
FINE STRUCTURE OF THE HUMAN OVUM IN THE PRONUCLEAR STAGE
Authors: Zamboni Luciano , Mishell Daniel R. , Bell James H. , Baca Manuel
Published: May 2004

A penetrated ovum was recovered from the oviduct of a 33 year old surgical patient who had had sexual intercourse 26 hr before the operation. The ovum was in the pronuclear stage. The ooplasmic organelles were mainly represented by mitochondria, endoplasmic reticulum components, and Golgi elements. Small vesicles were found in the space between the two sheets of the pronuclear envelope. These vesicles appeared to be morphologically similar to the ER vesicles in the ooplasm and were considered to be involved in pronuclear development. Numerous annulate lamellae were seen in the ooplasm as well as in the pronuclei. Ooplasmic crystalloids were also observed. These were thought to represent cytoplasmic yolk. Remnants of the penetrating spermatozoon were found in close relation to one of the pronuclei. The fine structure of the first and second polar body is also described. The nuclear complement of the first polar body consisted of isolated chromosomes, whereas the second polar body contained a membrane-bounded nucleus. In consideration of the possibility that polar body fertilization may take place, these differences in nuclear organization could be of importance. Other recognizable differences between the two polar bodies were presence of dense cortical granules and microvilli in the first polar body, and absence of these structures in the second. These dissimilarities were considered to be related to the organization of the egg cytoplasm at the time of polar body separation.
UNE FORME MICROTUBULAIRE ET PARACRISTALLINE DE RETICULUM ENDOPLASMIQUE DANS LES PHOTOCYTES DES ANNELIDES POLYNOINÆ
Authors: Bassot J. M.
Published: May 2004

Luminous cells of polynoid worm elytra have been examined by methods of electron microscopy, with special attention focused on the fine structure of photogenic grains. These cells send apical prolongations into the mid-part of the elytra. The plasma membrane is very sinuous, and a special kind of desmosome links two portions of the same membrane. In addition to all the organelles which can be found in nonluminescent epithelial cells of the elytra, numerous photogenic grains are contained in their cytoplasm. These grains are composed of undulating microtubules measuring 200 A in diameter; their disposition in the grain is highly regular, and the grains appear as paracrystals. At the borders of the grains, the walls of the microtubules are often in continuity with those of the endoplasmic reticulum and with the external membrane of the nuclear envelope. Because of this fact, the microtubules of the grains may be considered a cytoplasmic organelle, representing a specialized form of the endoplasmic reticulum. The microtubules permit the repartition, inside and outside their walls, of two different products, one being forty-three times more abundant than the other; thus, the contact surface, in comparison to the volume, is greatly increased. The induction of the luminous reaction by change in the permeability of the microtubule walls, allowing contact between the two substances, is suggested as a working hypothesis.

There is an evolution of the grains along the axis of the photocytes. The grains are often surrounded by progressively increasing amounts of glycogen. Their paracrystalline disposition is altered at the apex of the luminous cells.
THE FINE STRUCTURE AND CHEMICAL COMPOSITION OF NUCLEI DURING SPERMIOGENESIS IN THE HOUSE CRICKET
Authors: Kaye Jerome S. , McMaster-Kaye Rachel
Published: May 2004

The early stages of nuclear differentiation in spermatids of the house cricket are described with regard to the fine structural elements and chemical components which occur. Particular attention is given to the loss of nonhistone protein from the nucleus and its relation to chromatin structure. Granular elements about 25 to 80 mµ in diameter, and fibers about 8 mµ in diameter occur in the earliest spermatid nucleus. The fibers are found in diffuse and condensed chromatin while granules are found only in diffuse material. DNA and histone parallel the chromatin fibers in distribution, while nonhistone protein and RNA parallel the granules in distribution. The granules and most of the nonhistone protein are lost, simultaneously, after the early spermatid stage. The protein loss occurs without detectable change in the structure of chromatin fibers. Chromatin fibers first show a structural change in mid spermiogenesis, when they become thicker and very contorted. Unusually thin fibers (about 5 mµ) also appear in mid spermatid nuclei; they are apparently composed of nonhistone protein and free of DNA and histone.
ISOLATION OF METAPHASE CHROMOSOMES FROM HELA CELLS
Authors: Huberman Joel A. , Attardi Giuseppe
Published: May 2004

The authors have developed a method for large-scale isolation of metaphase chromosomes from HeLa cells. The distinguishing feature of this method is the use of a pH sufficiently low (about 3) to stabilize the chromosomes against mechanical damage. Many milligrams of fairly pure, morphologically intact chromosomes can be isolated in 8 hr or less of total working time. The isolated chromosomes contain about 2.0 mg of acid-soluble protein, 2.7 mg of acid-insoluble protein and 0.66 mg of RNA for each milligram of DNA. The RNA bound to the isolated chromosomes consists mainly of ribosomal RNA, but there is also a significant amount of 45S RNA.
THE EFFECTS OF ADENOSINE TRIPHOSPHATE AND RELATED COMPOUNDS ON SOME HYDRODYNAMIC PROPERTIES OF GLYCERINATED CILIA
Authors: Raff Elizabeth C. , Blum J. J.
Published: May 2004

Cilia were isolated from Tetrahymena pyriformis by a glycerol method. The addition of low concentrations of ATP, but not of other nucleoside triphosphates, caused an increase of up to twofold in the amount of cilia pelleted in a low-speed centrifugation assay and decreased the density of the pellets compared to control pellets. Pellet size and density depend on pH, both in the absence and in the presence of low concentrations of ATP. High concentrations (5 mM and above) of ATP and of other nucleoside triphosphates tend to "dissolve" the cilia. Heating the cilia for 11 min at 40°C abolishes the increase in pellet size and the decrease in pellet density caused by low ATP, but slightly increases the ATPase activity of the cilia. Heat treatment, however, does not prevent the dissolving effect of high ATP. There are, thus, two independent effects of ATP on the hydrodynamic properties of cilia suspensions.
OVARIAN STEROID CELLS
Authors: Blanchette E. Joan
Published: May 2004

The lutein cells of the rabbit exhibit fine structural variations during their life-span of 28 to 30 days. A systematic examination of the corpus luteum reveals that cellular distinctions may be recognized during the first, second, and third stages of pregnancy. The agranular endoplasmic reticulum reveals vesicular, tubular, and cisternal profiles after fixation with each of the following fixatives: glutaraldehyde, osmium tetroxide, and permanganate. The osmolality of the fixing solutions was varied with sucrose and recorded with an osmometer in order to determine the effect of osmotic concentration on the intracellular membranous profiles. It was determined that vesicles and short, branched tubules of similar structure are present in the agranular reticulum when the osmolalities are 300 to 800 milliosmols (iso-osmotic considered 300 milliosmols). At 900 milliosmols, the vesicular or tubular lumen is obliterated. Intracellular membrane profiles do not exhibit interconversions due to hyperosmotic fixative solutions. The agranular endoplasmic reticulum is randomly distributed as short tubular profiles during the first third of pregnancy. A continuity between these membranes and irregular, electron-opaque lipid masses is evident. When physiological and histochemical data indicate that the lutein cell may be storing sterol precursors, cytological observations show that the agranular endoplasmic reticulum exists in a more organized pattern within the cytoplasmic matrix. Vesicular and short tubular, circular aggregations as well as whorled cisternal patterns surround the larger, less electron-opaque lipid droplets. Surface views of cisternal agranular endoplasmic reticulum exhibit tubular extensions, accentuating the continuity between these two profiles. During the progress of pregnancy, the lutein cell increases in diameter, and accumulates both lipid inclusions and aggregations of intracellular membranes. The agranular endoplasmic reticulum may be peripherally packed and arranged parallel to the cell surface during later stages. In the postpartum, degenerating lutein cell, large myelin figures are present which form from the agranular endoplasmic reticulum. These cellular events are discussed in relation to lutein cell activity, including both secretion of product and storage of precursors.
PERSISTENCE OF NUCLEOLI IN SHORT TERM AND LONG TERM CELL CULTURES AND IN DIRECT BONE MARROW PREPARATIONS IN MAMMALIAN MATERIALS
Authors: Heneen Waheeb K. , Nichols Warren W.
Published: May 2004

Persistent nucleoli were studied in Chinese hamster and human long term cultures, human peripheral blood short term cultures, as well as direct bone marrow preparations. No colchicine or hypotonic treatments were applied and the cells were differentially stained with the Feulgen method and light green. Nucleoli were found to persist in the three systems studied, although to a much greater extent in the long term culture. The persistent nucleolar materials were usually in the form of individualized nucleoli mainly at chromosome ends. They also sometimes existed in a fluidlike or dropletlike condition around the chromosomes. Association of acrocentrics in humans and end-to-end associations in hamsters are likely to result from persistence of nucleoli and the possible effects of colchicine and hypotonic treatments that are usually applied. Other phenomena, such as stickiness at metaphase and separation difficulties and fragmentation at anaphase, may result from persistence of nucleoli. Nucleoli were often associated with large chromosomes and sometimes at sites exhibiting faint or clear constrictions. The possibilities of a partial correspondence between sites of persistence and sites of organization, as well as of the organization of nucleolar materials at sites other than the main organizers, are discussed. The persistent nucleoli were not included in daughter nuclei. They either degenerated in the cytoplasm or were eliminated from the cell. The three systems used may represent different intensities of metabolism reflected in the amounts of nucleolar materials built up and the amount that persists.
MICROTUBULES AND FILAMENTS IN THE AXONS AND ASTROCYTES OF EARLY POSTNATAL RAT OPTIC NERVES
Authors: Peters Alan , Vaughn James E.
Published: May 2004

Changes in the population of microtubules and filaments within the cytoplasm of maturing axons and astrocytes have been studied during the early postnatal development of rat optic nerves. At birth, all of the axons are unmyelinated; most have a diameter of 0.2–0.3 µ and contain 4–10 microtubules. Neurofilaments do not occur with any frequency until about 5 days postnatal when they appear as individual groups, each containing 4–12. Subsequently, the neurofilaments of each group disperse so that they become more evenly distributed in mature axons. Developing astrocytes show similar but rather more dramatic changes. Most astrocytic processes contain only microtubules at birth, but during maturation filaments begin to appear in increasing numbers while microtubules become less common. This process continues until, in the mature fibrous astrocytes, filaments pack the cytoplasm and microtubules are rare. These observations suggest that the filaments within axons and astrocytes may be formed by the breakdown of microtubules.
A FINE STRUCTURAL STUDY OF CYTODIFFERENTIATION DURING CLEAVAGE, BLASTULA, AND GASTRULA STAGES OF FUNDULUS HETEROCLITUS
Authors: Lentz Thomas L. , Trinkaus J. P.
Published: May 2004

The fine structure of cleavage, blastula, and gastrula stages of Fundulus heteroclitus was investigated. Cleavage blastomeres are relatively unspecialized, containing few or poorly developed organelles. Beginning in blastula stages, signs of differentiation were noted, including development of the endoplasmic reticulum and Golgi apparatus and appearance of a primary nucleolus and polyribosomes. More extensive structural specializations occur in gastrula stages, including further development of the endoplasmic reticulum and appearance of a granular component in the nucleolus. These changes are associated with cell differentiation and an increased capacity for protein synthesis, and may be preparatory to subsequent histogenesis. The periblast is a continuous syncytial cytoplasmic layer located between the blastodisc and yolk and is formed during late cleavage by incomplete division of the cytoplasm of the blastodisc. Cytoplasmic projections extend from the periblast (and from the basal region of cleavage blastomeres prior to formation of the periblast) into the yolk and function in uptake of yolk material in the absence of pinocytosis. Yolk material appears to be digested by the periblast and transferred into the segmentation cavity where it is available to the blastomeres. Protein granules, lipid droplets, glycogen, crystalline arrays, and multivesicular bodies are related to food storage and utilization by blastomeres. The yolk gel layer enclosing the yolk sphere was found to be a thin layer of cytoplasm continuous with the margin of the periblast and is renamed the yolk cytoplasmic layer.
TRANSIENT HOLES IN THE ERYTHROCYTE MEMBRANE DURING HYPOTONIC HEMOLYSIS AND STABLE HOLES IN THE MEMBRANE AFTER LYSIS BY SAPONIN AND LYSOLECITHIN
Authors: Seeman Philip
Published: May 2004

Ferritin and colloidal gold were found to permeate human erythrocytes during rapid or gradual hypotonic hemolysis. Only hemolysed cells contained these particles; adjacent intact cells did not contain the tracers. Ferritin or gold added 3 min after the onset of hypotonic hemolysis did not permeate the ghost cells which had, therefore, become transiently permeable. By adding ferritin at various times after the onset of hemolysis, it was determined that for the majority of the cells the permeable state (or interval between the time of development and closure of membrane holes) existed only from about 15 to 25 sec after the onset of hemolysis. It was possible to fix the transient "holes" in the open position by adding glutaraldehyde only between 10 and 20 sec after the onset of hemolysis. The existence of such fixed holes was shown by the cell entry of ferritin and gold which were added to these prefixed cells. Membrane defects or discontinuities (of the order of 200–500 A wide) were observed only in prefixed cells which were permeated by ferritin subsequently added. Adjacent prefixed cells which did not become permeated by added ferritin did not reveal any membrane discontinuities. Glutaraldehyde does not per se induce or create such membrane defects since cells which had been fixed by glutaraldehyde before the 10-sec time point or after the 180-sec time point were never permeable to added ferritin, and the cell membranes never contained any defects. It was also observed that early in hemolysis (7–12 sec) a small bulge in one zone of the membrane often occurred. Ghost cells produced by holothurin A (a saponin) and fixed by glutaraldehyde became permeated by ferritin subsequently added, but no membrane discontinuities were seen. Ghosts produced by lysolecithin and fixed by glutaraldehyde also became permeated by subsequently added ferritin, and many membrane defects were seen here (about 300 A wide).
THE MITOTIC APPARATUS
Authors: Kane R. E.
Published: May 2004

Mitotic apparatuses (MA) isolated from metaphase sea urchin eggs in 12% hexylene glycol at pH 6.4 can be dissolved rapidly in 0.6 M KCl, and more than one-half of the total protein of the MA is soluble under these conditions. In the phase-contrast microscope, the fibrous structure of the MA can be seen to disintegrate in KCl solution, leaving only granular material which, in the electron microscope has been seen to be largely vesicular, with no evidence of microtubules or other fibrous elements. The KCl-soluble material thus must contain the soluble components of the microtubules and consists of one major, homogeneous component with a sedimentation coefficient of 22 Svedbergs, and a much smaller amount of more heterogeneous material sedimenting at 4-5S. A component similar to the 22S component can be identified in extracts of unfertilized eggs, where it forms approximately 8% of the total cell protein. The amount of this protein present in the cell is considerably in excess of that involved in the MA, as can be shown by its presence in the soluble supernate from a mitotic apparatus isolation. This protein must form part of, or be associated with, the fibrous structure of the MA in some fashion that allows its release only upon the dissolution of the mitotic apparatus.
THE MITOTIC APPARATUS
Authors: Stephens R. E.
Published: May 2004

The major 22S protein of the hexylene glycol-isolated mitotic apparatus has been characterized from spindle isolates and extracts of whole eggs and acetone powders of eggs from the sea urchins Strongylocentrotus purpuratus, Strongylocentrotus droebachiensis, and Arbacia punctulata. The protein is free of nucleotide, lipid, and ATPase activity. Essentially identical in amino acid composition, proteins from these species show a relatively high content of glutamic and aspartic acids and are fairly rich in hydrophobic amino acids. Optical rotatory dispersion studies indicate a helical content of about 20%, a value consistent with the proline content of the protein. The purified proteins have sedimentation rates in the range of 22–24S, diffusion constants of 2.4–2.5F, intrinsic viscosities of 3.7–4.3 ml/g, a partial specific volume of 0.74, and an average molecular weight of 880,000. Electron microscopy indicates a globular molecule with dimensions of approximately 150 by 200 A; such size and symmetry are consistent with hydrodynamic measurements. The 22S protein yields 6–7S, 9–10S, and 13–14S subunits below pH 4 or above pH 11. The 13–14S component has an estimated molecular weight of 600,000–700,000. A 5–6S particle is formed in 8 M urea or 5 M guanidine hydrochloride, while at pH 12 the 6–7S subunit is seen; each particle has a molecular weight of 230,000–240,000. In 8 M urea plus 2% mercaptoethanol or at pH 13, the molecular weight becomes 105,000–120,000; under these conditions the particle sediments at 2.5–3S and 4S, respectively. On the basis of these molecular weights, the 6–7S, 9–10S, 13–14S, and the parent 22S particle should be dimer, tetramer, hexamer, and octamer, respectively, of the 105,000–120,000 molecular weight subunit. The various subunits will reform the 22S particle when returned to neutral buffer, with the exception of the mercaptoethanol-treated urea subunit where breakage of disulfide bonds results in a polydisperse aggregate. The 22S particle itself is not susceptible to sulfhydryl reagents, implying either that the disulfide bonds are inaccessible or that they are unnecessary for maintenance of tertiary structure once the 22S particle has formed from subunits.