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  • Life and Medical Sciences  (268)
  • 1975-1979  (170)
  • 1970-1974  (98)
  • 1
    Electronic Resource
    Electronic Resource
    Tissue microenvironment and the genetic control of hair pigment patterns in mice (1979)
    Chichester [u.a.] : Wiley-Blackwell
    Developmental Genetics 1 (1979), S. 167-179 
    Details
    ISSN: 0192-253X
    Keywords: agouti locus ; hair pigment patterns ; melanocyte metabolism ; tissue microenvironment ; eumelanin ; phaeomelanin ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: This study was conducted to assess microenvironmental variability within integumental tissue of genetically identical mice with respect to a specific cellular response: cyclic synthesis of yellow and black pigment by hair bulb melanocytes. Crosses were performed within and between inbred strains of mice that were isogenic with the exception of a single gene substitution at the agouti locus. Agouti locus genes included the Avy, Aw, A, atd, at, ax, am, and a alleles. The pigment patterns of dorsal, flank, and ventral hairs of the first and third hair generations and of hairs growing in special integumentary areas such as the pinna, tail, and hind foot were studied. It was found that the amount of yellow pigment synthesized by hair bulb melanocytes within genetically identical mice is both agedependent and conditioned by the integumentary environment. Furthermore, the special integumentary regions produce hairs with a variety of pigment patterns in which the distribution and relative amounts of black and yellow pigments do not necessarily conform to dominance relationships expected among agouti locus alleles as judged by their effects on the pigmentation of the dorsal pelage. We conclude that within genetically uniform integumental tissues, microenvironmental differences occur and are reflected as alterations in the metabolic pattern of differentiated cells.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/dvg.1020010205
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  • 2
    Electronic Resource
    Electronic Resource
    Mutations specific to spore maturation in the asexual fruiting body of dicytostelium discoideum (1979)
    Chichester [u.a.] : Wiley-Blackwell
    Developmental Genetics 1 (1979), S. 355-362 
    Details
    ISSN: 0192-253X
    Keywords: Dictyostelium discoideum ; spore maturation ; spore specific mutations ; cell patterning ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: Three mutations affecting spore maturation in the asexual fruiting body of Dictyostelium discoideum are assigned to a new locus, sprJ, on linkage group IV. Strains carrying mutations at the sprJ locus do not form mature spores, yet the cell patterning (spore, stalk and disc cell ratios) is apparently normal. These mutations will be useful to delineate branch points between the cell patterning and spore maturation pathways. There are some unusual features of the sprJ-containing mutants. In particular each of the parent strains of the three mutants has incomplete spore maturation as determined by colony-forming ability after heat shocking at 45°C. A mutation allowing growth in the presence of benlate (600 μg/ml), benA351, is mapped to linkage group I.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/dvg.1020010408
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  • 3
    Electronic Resource
    Electronic Resource
    Histogenesis of Swiss white mouse secondary palate from nine and one-half days to fifteen and one-half days In utero. I. Epithelial-mesenchymal relationships - light and electron microscopyThis work was supported by Research grant DE 03002 from the National Institute of Dental Research, NIH. (1970)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 130 (1970), S. 435-449 
    Details
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Development of the secondary palate in Swiss white mouse embroyos was studied from age nine-and-one-half days in utero to the stage of mesenchymal coalescence in the secondary palate (approximately fifteen-and-one-half days). The greatest changes observed occur in the mesenchyme. At early stages, mesenchymal cells underlying oral ectoderm of the head are few and only occasionally contact the ectoderm. Electron micrographs show large intercellular spaces between the ectodermal cells. As embryogenesis continues, the mesenchymal cells become more numerous, closer to each other and closer to the epithelium. Just prior to horizontal transposition of shelves, the mesenchymal cells spread farther from each other and from the palatal epithelium and epithelium of the palatal tip becomes stretched. Ultrastructurally the intercellular spaces between epithelial cells of the palate tip have become much smaller. Some mitochondria in some epithelial cells are swollen and have clear matrices and distorted cristae. The shelves become horizontal and meet in the midpalate. Cells with degeneration bodies are seen in the epithelial seam. The seam undergoes autolysis and is replaced by mesenchyme. The morphological changes described, particularly in the mesenchyme, may play an important role in determining the effect of various teratogens at different stages of palatal development. The changes in both mesenchyme and epithelial cells in the later stages may constitute part of the process of preparing shelves for fusion as postulated by Pourtois ('66).
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jmor.1051300404
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  • 4
    Electronic Resource
    Electronic Resource
    Salivary gland development in the blowfly, Calliphora erythrocephala (1976)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 149 (1976), S. 459-482 
    Details
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The salivary gland of adult Calliphora erythrocephala is a tubular structure composed of secretory, reabsorptive, and duct regions. Development of these structures has been followed during the six days of larval and ten days of pupal growth. Two small groups of imaginal cells located at the junction between larval gland and duct give rise to the adult gland. These presumptive adult cells divide during all larval stages and appear to be functional components of the larval gland. Shortly after pupation, the larval gland breaks down and the imaginal cells proliferate rapidly, forming sequentially the duct, reabsorptive and secretory regions. Proliferating regions of the developing gland are frequently encrusted with haemocytes. As it elongates the gland establishes intimate contacts first with the basement membrane of the degenerating larval gland, later with an epithelial layer surrounding the main dorsal tracheal trunks, and then with the gut. Cell division continues until about five days after pupation, bu t the gland is unable to secrete fluid in response to 5-hydroxytryptamine stimulation until two hours after the adult fly emerges. The Golgi complex appears to be involved in forming the highly folded membranes of the canaliculi in the secretory region.Presumptive adult salivary gland cells appear to increase in number logarithmically from the time of hatching of the larva until five days after pupation. This contrasts with the development of classical imaginal discs, in which cell division ceases prior to pupation.
    Additional Material: 35 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jmor.1051490403
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  • 5
    Electronic Resource
    Electronic Resource
    Mechanics of the syrinx in Gallus gallus. II. Electromyographic studies of Ad Libitum vocalizations (1977)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 152 (1977), S. 1-19 
    Details
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Records of electrical activity in the tracheal muscles of domestic chickens were obtained for a variety of ad libitum vocalizations. Primary attention was given to an analysis of events during the most complex call, crowing.Three pairs of muscles, Mm. tracheohyoideus, tracheolateralis, and sternotrachealis, can affect the configuration of a chicken's syrinx. The firing patterns of the three muscle pairs are related to their different abilities to affect the tension of the syringeal membranes. The influence of M. tracheohyoideus is most indirect and imprecise, and its role the least clearly defined. It appears to adjust the position of the trachea so that the syrinx is isolated from unpredictable and/or undesirable consequences of nuchal position and tracheal elasticity, and also helps draw the glottis caudad, thereby deepening the pharyngeal chamber. The other two muscles interact to control the tension of the vocal membranes. M. sternotrachealis relaxes the membranes by drawing the drum of the trachea caudad, or, via the syringeal ligament, by rotating the pessulus cranioventrad, or both. M. tracheolateralis tenses the membranes and/or prevents caudal movement of the origin of M. sternotrachealis, a necessity if the syringeal ligament is to rotate the pessulus.Vocalization depends on both syringeal configuration and appropriate air flow. Hence, tracheal muscles, syrinx, air sacs, and ventilatory muscles cooperate to form a vocal system. Cooperation elicits a surprising degree of redundancy. At least one call, a high pitched wail, may be produced by two very different techniques.
    Additional Material: 12 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jmor.1051520102
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  • 6
    Electronic Resource
    Electronic Resource
    Susceptibility to polycythemia of hemopoietic spleen colonies produced by cultured embryonal liver cells (1971)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Cellular Physiology 78 (1971), S. 405-410 
    Details
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The survival of colony-forming cells in organ cultures of the mouse embryonal liver was studied. During cultivation colony-forming cells acquire the type of regulation characteristic of the adult organism. Factors affecting the change in the type of regulation from embryonal to adult of the hemopoietic stem cells in cultures are discussed.
    Additional Material: 2 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcp.1040780309
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  • 7
    Electronic Resource
    Electronic Resource
    Selective and nonselective isolation of temperature-sensitive mutants of mouse L-cells and their characterizationSupported by the Medical Research Council of Canada and the National Cancer Institute of Canada. (1971)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Cellular Physiology 78 (1971), S. 431-439 
    Details
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Mutants of mouse L-cells which are temperature-sensitive for growth have been obtained by using both selective and nonselective isolation procedures on populations treated with the mutagen nitrosoguanidine. Selective isolation was carried out by utilizing a five-day treatment with 3H-TdR and ara-C as selective agents at the nonpermissive temperature. Nonselective isolation was performed by isolating 1400 clones in the absence of selective agents and then testing them for temperature-sensitivity. From this experiment we obtained a minimum estimate of 6 × 10-3 for the frequency of mutants in the mutagentreated population. The mutants were characterized by their plating efficiencies, growth in suspension culture, and uptake of isotopic precursors of DNA, RNA, and protein. A range in phenotypes was observed, and there appeared to be some differences between the mutants obtained by the two types of isolation procedures. In uptake experiments the most marked reductions in the rates of precursor incorporation were seen with 3H-TdR, rather than 3H-UR or 3H-Leu. Different mutant lines showed considerable variation in the rate of cessation of DNA synthesis as well as the time required for termination of cell division. These experiments suggest that both types of isolation procedures are feasible for obtaining temperature-sensitive mutants having a range of phenotypes.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcp.1040780312
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  • 8
    Electronic Resource
    Electronic Resource
    Proliferation of hemopoietic stem cells in culture of embryonal liver of mice (1971)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Cellular Physiology 78 (1971), S. 461-463 
    Details
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The vinblastine technique was used to demonstrate that the proliferative capacity of colony-forming cells in organ culture of embryonal liver of mice between the first and seventeenth day of cultivation is adequately high. The relative content of CFU increases in culture with a maximum between one and two weeks.
    Additional Material: 1 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcp.1040780315
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  • 9
    Electronic Resource
    Electronic Resource
    Glycolytic enzyme activity in developing red and white muscle (1974)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Cellular Physiology 83 (1974), S. 251-257 
    Details
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The activities of the constant proportion enzymes of the Embden-Meyerhof chain (triose phosphate isomerase (TIM), glyceraldehyde-3-phosphate dehydrogenase (GAPDH), phosphoglycerate kinase (PGK), phosphoglycerate mutase (PGM) and enolase (ENOL)), and the activity of lactic dehydrogenase (LDH) were studied in developing red (trapezius) and white (longissimus) muscles of the pig from a fetal stage to 24 weeks postnatal. Both muscles were differentiated by two weeks postnatal in the sense that they had reached the adult level of enzyme activity. Enzyme activities were two- to three-fold greater in the longissimus than in the trapezius. Enzyme activity ratios based on GAPDH were not consistent in the fetal and day 1 samples but were consistent during later stages of growth. Ratios of enzyme activity based on activity at 105 days gestation revealed that TIM, PGK and PGM are grouped and follow the same pattern, but GAPDH and ENOL are quite different from each other and from the pattern shown by TIM, PGK and PGM. The constant proportion concept in developing muscle is therefore questioned.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcp.1040830211
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  • 10
    Electronic Resource
    Electronic Resource
    Centrifugal elutriation: Separation of spermatogenic cells on the basis of sedimentation velocity (1975)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Cellular Physiology 86 (1975), S. 177-189 
    Details
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Various types of cells from the testes of mice and hamsters were separated according to differences in sedimentation velocity by centrifugal elutriation, a counterflow centrifugation technique. Approximately 3 × 108 cells, prepared from six mouse testes or from one hamster testis, were separated into 11 fractions in less than two hours as compared to the 4-5 hours required for sedimentation at unit gravity (“Staput”). Fractions enriched in elongated spermatids and spermatozoa (100%), stages 1-8 spermatids (69%) and pachytene spermatocytes (58%) were obtained from mouse testis dispersions. Similarly enriched fractions were obtained from hamster cells. A single fraction enriched in stages 1-8 spermatids (mouse) was prepared in less than 30 minutes. As many as 2 × 109 cells were separated in a single procedure. Spermatogenic cells exhibited no evidence of structural damage with trypan blue and phase microscopy, and recovery was essentially 100%. Centrifugal elutriation had no effect on sperm motility or on the plating efficiency of CHO cells.
    Additional Material: 4 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcp.1040860119
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