Showing papers in "Experimental Cell Research in 1955"

TL;DR: The ultrastructure of the nuclear membrane from sea urchin and starfish oocytes has been studied by means of electron microscopy in ultra-thin sections prepared according to the technique of Sjostrand to identify irregular extra-nuclear membrane with the same structure as that described in point 1.

TL;DR: Cell growth in volume and protein, and growth in the volume of the nucleus were followed over the cell cycle employing small groups of amoebae in synchronous growth, and nuclear growth is rapid following division but falls to a lower rate during most of the interphase.

TL;DR: On ultrathin sections of chloroplasts from Aspidistra elatior the electron microscopic study has revealed that the grana consist of layered columns, which shows obvious tendencies to swell in hypotonic media.

TL;DR: L'etude au microscope electronique du nucleole de cellules normales & cancereuses permet de preciser l'ultrastructure de cet organite d'un element reticule ou filamenteux and de zones intra et perinucleaires plus diffuses.

TL;DR: It appears that completion of DNA synthesis occurs about the time chromosomes first behave as double entities to X-rays, and there can be no generalized period in the division cycle whenDNA synthesis occurs; it seems to depend on the nature of the division.

TL;DR: The staining of the fibroblasts suggests the possibility that a ribonucleoprotein may be the agent responsible for “bubbling”, which is related temporally to nuclear changes and spatially to the chromosomes in ways that suggest that they arise in response to an agent released by the chromosomes.

TL;DR: The kinetics of various transport systems across cell membranes involving chemical reactions of the transported substrate in the membrane (with and without carrier molecules) have been worked out for the steady state and the mechanism of coupling to energy-supplying reactions, resulting in accumulation, has been considered.

TL;DR: An improved optical system for microspectrophotometry was designed and constructed with succesful result to eliminate the S-V effect completely, and its details were described.

TL;DR: A separation approaching the ideal is obtained by the use of more dilute breis, careful layering over a continuous density gradient sufficiently steep to prevent the anomalies mentioned, and a rigid adherence to a gradual acceleration and deceleration schedule.

TL;DR: Preliminary results with a simple method of tissue culture which provides a continuous gradient in cell number, oxygen tension, oxidation-reduction potential, and cell conditioning factors are described and pictured.

TL;DR: The chromosomes showed a very similar interphase sensitivity to breakage by the two agents, i.e. the maximum effect was obtained with EOC as well as with X-rays when the cells were treated at late interphase.

TL;DR: Model experiments suggest that reaction products from unsaturated fatty acids and osmium tetroxide are unable to pass through natural membranes and results in increased extractability with water.

TL;DR: The change that enables tumor cells to multiply in the peritoneal fluid has been found to be correlated with a reduction of cellular adhesiveness and an increased capacity to metastasize to the lungs.

TL;DR: Good quality lymphocytes and cell differentiation were only obtained when the medium contained both cocarboxylase and p-aminobenzoic acid, and the optimum concentrations of these substances were determined.

TL;DR: The intensity of the arg and its localisation vary with the amount and distribution of the cytoplasm in the different types of cartilage; this accounts for the ‘ring’-like appearance in the ear and in the fibrocartilage of the xiphoid and for the more uniform appearance over the cells of hyaline cartilage.

TL;DR: The nucleic acid determinations show that the mean DNA content per cell steadily increases with distance from the root apex, being 30 per cent greater in the proximal segment, which is composed mainly of fully differentiated cells, than in the terminal segment,Which is entirely meristematic.

TL;DR: The hyaline layer might play and important role in the final establishment of the block to polyspermy, because thin hyaline layers could be penetrated by refertilizing spermatozoa, and the presence of unfertilized cortex in partially fertilized eggs was found to retard or arrest some of the processes associated with early and late development.

TL;DR: Cytochrome oxidase activity increases in the embryo throughout the prefeeding period of development, and at all stages tested, the enzyme appears to be localized in the mitochondrial fraction of embryo homogenates.

TL;DR: Embryonic chick spinal cord in advanced stages of differentiation was dissociated into its constituent cells by trypsin digestion followed by mechanical separation, which lends itself readily to studies of single neurons, as well as their reactions to controllable influences of the medium and of other cell types.