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  • 1990-1994  (15)
  • 1965-1969  (3)
  • Life and Medical Sciences  (16)
  • Ideal free distribution  (2)
  • 1
    Electronic Resource
    Electronic Resource
    Uganda kob mating success does not increase on larger leks (1994)
    Springer
    Behavioral ecology and sociobiology 34 (1994), S. 451-459 
    Details
    ISSN: 1432-0762
    Keywords: Lek-breeding ; Mating systems ; Socioecology ; Ideal free distribution
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract One explanation for the movement of sexually receptive females to clusters of male territories in lek-breeding species is that larger clusters provide females with higher-quality mating partners, as would be the case if males were distributed between leks in an ideal free distribution for unequal competitors. This ideal free model of lek evolution predicts that male competitive ability and mating success will be greater on larger leks than smaller ones. I tested these predictions by comparing the mean number of males on 19 different Uganda kob leks with the sex ratio, the availability of oestrous females, mating rates, male fighting rates and male turnover rates. Contrary to the predictions of the model, numbers of females, receptive females and fights increased proportionally with lek size, but were no greater per male on larger leks. Multivariate analyses of male and female numbers on leks showed that male numbers were associated with female numbers, female numbers in the past, and a variety of habitat variables which may have related to the costs of holding a lek territory, but female numbers varied only with male numbers and female density in the area. These data do not provide evidence that females gain access to superior males by mating on larger leks, though they do support the possibility that lekking may be promoted by a tendency for larger leks to retain females longer.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00167337
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  • 2
    Electronic Resource
    Electronic Resource
    Middle-ear development: II. Morphometric changes in the conducting apparatus of the chick (1992)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 212 (1992), S. 257-267 
    Details
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The ontogeny of various middle-ear structures was examined in 11 groups of chicks between 10 days embryonic and adult. Measurements of the tympanic membrane surface area and height, columella length, and that of the columella footplate, annular ligament, and oval window area were obtained using video micrographs and computer digitization techniques. The oval window matures first at 53 days post-hatching, whereas the columella achieves adult size at 74 days. The tympanic membrane surface area is the last middle-ear variable studied to reach adult size (79 days post-hatch). The columella increases its length from 0.63 mm (10 days embryonic) to 2.73 mm in the adult. The tympanic membrane area expands by 280% whereas the columellar footplate area increases by 11x. As a result, the pressure amplification of the middle ear due to the tympanic membrane/columellar footplate area ratio improves by over 400%. These data further contribute to our understanding of the functional development of the middle ear. © 1992 Wiley-Liss, Inc.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jmor.1052120305
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  • 3
    Electronic Resource
    Electronic Resource
    Uganda kob mating success does not increase on larger leks (1994)
    Springer
    Behavioral ecology and sociobiology 34 (1994), S. 451-459 
    Details
    ISSN: 1432-0762
    Keywords: Key words: Lek-breeding ; Mating systems ; Socioecology ; Ideal free distribution
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract. One explanation for the movement of sexually receptive females to clusters of male territories in lek-breeding species is that larger clusters provide females with higher-quality mating partners, as would be the case if males were distributed between leks in an ideal free distribution for unequal competitors. This ideal free model of lek evolution predicts that male competitive ability and mating success will be greater on larger leks than smaller ones. I tested these predictions by comparing the mean number of males on 19 different Uganda kob leks with the sex ratio, the availability of oestrous females, mating rates, male fighting rates and male turnover rates. Contrary to the predictions of the model, numbers of females, receptive females and fights increased proportionally with lek size, but were no greater per male on larger leks. Multivariate analyses of male and female numbers on leks showed that male numbers were associated with female numbers, female numbers in the past, and a variety of habitat variables which may have related to the costs of holding a lek territory, but female numbers varied only with male numbers and female density in the area. These data do not provide evidence that females gain access to superior males by mating on larger leks, though they do support the possibility that lekking may be promoted by a tendency for larger leks to retain females longer.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00167337
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  • 4
    Electronic Resource
    Electronic Resource
    The passage of exogenous peroxidase from blood capillaries into the intestinal epithelium (1967)
    New York, NY [u.a.] : Wiley-Blackwell
    The @Anatomical Record 159 (1967), S. 159-169 
    Details
    ISSN: 0003-276X
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: Horseradish peroxidase was injected into the spleens of mice and the animals were sacrificed ten minutes after injection. The tissues were reacted with 3-3′ diaminobenzidine hydrochloride and the distribution of the reaction product was studied with both the light and electron microscope. The peroxidase was localized between epithelial cells up to the region of the tight junction and within vacuoles in the absorptive cells Granules ranging in size from ca. 40A to 600A were observed in the cytoplasm of epithelial cells in numbers far in excess of that found in control specimens. It appeared that the diffuse light brown staining observed in epithelial cells with the light microscope could be attributed to large numbers of granules of reaction product free in the cytoplasm. When corn oil was given by stomach tube and an intravascular injection of perioxidase was given ten minutes later, absorbed lipid was found to pass from interepithelial cell spaces to lamina propria at the same time that peroxidase was traversing the same compartments in the reverse direction. Hence, it was shown that exogenous peroxidase and probably other substances of vascular origin required for the metabolism of epithelial cells are exposed to both the basal and lateral epithelial cell membranes, even when absorbed lipid is traversing the same spaces in the opposite direction.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ar.1091590205
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  • 5
    Electronic Resource
    Electronic Resource
    Middle-ear development VI: Structural maturation of the rat conducting apparatus (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    The @Anatomical Record 239 (1994), S. 475-484 
    Details
    ISSN: 0003-276X
    Keywords: Middle ear ; Auditory ; Hearing development ; Ossicles ; Tympanic membrane ; Rat (Long Evans strain) ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: Background: The contribution of middle-ear development to the overall development of hearing has not been explored in great detail. This presentation describes the maturation of conductive elements in the rat middle ear, and provides the basis on which future studies of middle-ear functional development will follow.Methods: The middle-ear apparatus was examined at nine different ages (between 1 and 80 days postpartum) in Long Evans rats. At each age elements of the conducting apparatus were observed with either light or scanning electron microscopy (SEM), and quantitative measurements were made from video enhanced photomicrographs. Tympanic membrane area and cone depth, the length of the malleus and incus arms, ossicular weight, stapes foot plate and oval window areas, and bulla volume were all measured. Development of the area and lever ratios were derived from these measurements. The data were fitted to exponential equations and the time in days required to reach 90% of the adult level determined.Results: The pars tensa achieved 90% of total area by 17 days. The oval window achieved the 90% criterion by 13 days, while the area ratio was within 10% of its adult size by 8 days. The ossicles took between 26 and 34 days, while bulla volume took 59 days to reach the 90% level.Conclusions: Middle-ear growth was very orderly and systematic in the data reported. When maturation of the area ratio was considered against development of the endocochlear potential or the round window compound action potential, it was clear that the growth of this important aspect of the middle ear preceded the onset of cochlear function. © 1994 Wiley-Liss, Inc.
    Additional Material: 12 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ar.1092390413
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  • 6
    Electronic Resource
    Electronic Resource
    Marginal zone and germinal center development in the spleens of neonatally thymectomized and nonthymectomized young ratsThis project received support from a General Research Support grant to the University of Wisconsin Medical School from the National Institutes of Health, Division of Research Facilities and Resources. (1968)
    New York, NY [u.a.] : Wiley-Blackwell
    American Journal of Anatomy 123 (1968), S. 489-499 
    Details
    ISSN: 0002-9106
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: Spleens from neonatally thymectomized and nonthymectomized young rats were studied histologically and histochemically to elucidate the development of the splenic immune system with and without thymus.In intact animals primitive germinal center activity could be elicited with antigen as early as 13 days of age. More definitive germinal centers lacking tingible body macrophages were observed at 18 days of age. Germinal centers containing tingible body macrophages did not develop until 35 days of age in response to antigenic stimulation. This coincided with maximal development of the marginal zone of medium-sized lymphocytes and the mature development of nodular macrophages possessing strong acid phosphatase activity.Neonatally thymectomized rats developed marginal zones and germinal centers similar to control littermates when the young animals were maintained on tetracycline. Thymectomized animals not given tetracycline showed disturbances in splenic development. These are discussed.The results suggest that the thymus may be critical to the immune system in rats from birth to about 30 days of age but is not essential to its function beyond this period. Marginal zone lymphocytes and germinal center cells proliferate normally and mature to the plasma cell stage in the absence of a thymus if the animals are maintained on tetracycline beyond this critical age.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aja.1001230306
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  • 7
    Electronic Resource
    Electronic Resource
    A morphological and histochemical study of the primary and secondary immune responses in the rat spleenThis project received support from a General Research Support Grant to the University of Wisconsin Medical School from the National Institutes of Health, Division of Research Facilities and Resources. (1967)
    New York, NY [u.a.] : Wiley-Blackwell
    American Journal of Anatomy 121 (1967), S. 305-317 
    Details
    ISSN: 0002-9106
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: Macrophages and cells of the plasmocyte series were studied in the rat's spleen during the primary and secondary immune responses to particulate antigen. Evidence is presented to suggest that the plasma cell precursors are located in the marginal zones surrounding the lymphoid nodules and that less than one day following injection of antigen, these cells migrate into the nodules, where mitosis and subsequent differentiation into hemocytoblasts occurs in the presence of nodular macrophages. The hemocytoblasts then migrate across the marginal zone into the red pulp where differentiation into mature plasma cells occurs in the presence of red pulp macrophages. It is suggested that the initiation of the antibody-forming process occurs in the lymphoid nodules where marginal zone cells come into close contact with the marginal metalophils or with germinal center macrophages. The process initiating the migration of cells from the marginal zone to the nodules is unknown.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aja.1001210209
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  • 8
    Electronic Resource
    Electronic Resource
    Immunohistochemical localization of atrial natriuretic peptide in the developing and adult mammalian kidney (1991)
    New York, NY [u.a.] : Wiley-Blackwell
    American Journal of Anatomy 190 (1991), S. 182-191 
    Details
    ISSN: 0002-9106
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: The discovery, within the last decade, of atrial natriuretic peptide (ANP), a family of peptides with natriuretic/diuretic and vasorelaxant properties, has prompted much research into the mechanisms and sites of action of ANP within the kidney. In the present study, ANP was localized in the kidneys of several mammalian species by immunohistochemical techniques (1) to identify possible sites of synthesis; (2) to compare the localization of ANP to known physiological effects; (3) to determine species differences, if any, in ANP localization; and (4) to study the development of ANP immunoreactivity in the fetal and neonatal rat kidney. Using an antibody against rat ANP IV, ANP was localized exclusively on the proximal convoluted tubule (PCT) brush border and within intercalated cells of the outer medullary and cortical collecting tubules and ducts of adult mouse, rat, pig, monkey, and human kidneys. The development of ANP immunoreactivity paralleled the differentiation and maturation of collecting duct epithelium in rat fetal kidney. Atrial natriuretic peptide found within intercalated cells of the cortical and outer medullary collecting ducts may be the result of endogenous synthesis and, following secretion, may be available to receptors in the inner medullary collecting ducts.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aja.1001900207
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  • 9
    Electronic Resource
    Electronic Resource
    PDGF-stimulated fibroblast proliferation is enhanced synergistically by receptor-recognized α2-Macroglobulin (1990)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Cellular Physiology 145 (1990), S. 1-8 
    Details
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: α-Macroglobulins derived from plasma or secreted by macrophages are plateletderived growth factor (PDGF) binding proteins that compete with cell-surface receptors on fibroblasts for PDGF binding. α2-Macroglobulin (α2M) derived from bovine plasma was tested for its ability to modulate the PDGF-induced proliferation of primary passage rat lung fibroblasts (RLFs) and a human skin fibroblast cell line (CRL 1508). Fibroblasts were grown in 10% fetal bovine serum (FBS) for 24 hr, then washed with serum-free medium before adding serum-free defined medium (SFDM) containing insulin and transferrin. To this medium were added varying concentrations of human plasma-derived AB-PDGF and α2M, alone or in combination. Receptor-recognized α2M was prepared by treatment with methylamine. Both native α2M and the α2M-methylamine (α2M-MA) were tested for growth promoting activity in the absence or presence of PDGF. After 3 days, a concentration-dependent growth curve of fibroblast proliferation was demonstrated for PDGF alone, with near maximal stimulation reached at 15-20 ng/ml PDGF. α2M and α2M-MA alone had no effect on cell proliferation. However, α2M-MA concentrations above 32 μg/ml synergistically enhanced PDGF-stimulated proliferation 〉100% in the presence of 15 ng/ml PDGF. Native α2M enhanced PDGF-stimulated growth 80-100% above PDGF controls only at low concentrations (32-64 μg/ml α2M). High concentrations of native α2M (128-256 μg/ml) either had no effect on growth or were inhibitory to PDGF-stimulated growth, depending on the cell type tested. Rat lung fibroblasts were shown to secrete a factor(s) that inhibited the trypsin-binding capacity of native α2M. We further demonstrated that early passage RLFs possess specific cell-surface receptors for [125I]-PDGF and [125I]-α2M-MA, and preincubation of RLFs with α2M-MA increased the specific binding of [125I]-PDGF to the cell surface of these fibroblasts. Considered together, these data support the view that receptor-recognized α2M synergistically enhances the proliferative capacity of PDGF. We postulate that receptor-recognized αMs enhance PDGF-stimulated growth by increasing the local concentration of PDGF at the cell surface, where the PDGF could be released in close proximity to its own receptors.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcp.1041450102
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  • 10
    Electronic Resource
    Electronic Resource
    Mechanism and regulation of neutrophil priming by platelet-activating factor (1993)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Cellular Physiology 156 (1993), S. 189-197 
    Details
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Although a weak direct stimulus of superoxide anion (O2-) production, platelet-activating factor (PAF) markedly enhances responses to chemotactic peptides (such as n-formyl-met-leu-phe, FMLP) and phorbol esters (such as phorbol myristate acetate, PMA) in human neutrophils. The mechanism of priming was explored first through inhibition of steps in the signal transduction pathway at and following PAF receptor occupation. Priming was not altered by pertussis toxin or intracellular calcium chelation, but the PAF receptor antagonist WEB 2086 and the protein kinase C (PKC) inhibitors sphinganine and staurosporine significantly inhibited the primed response. In order to study the regulation of PAF priming, the effect of PAF alone was desensitized by exposure to escalating doses of PAF prior to exposure to the secondary stimuli. The priming effect of PAF was not desensitized under these conditions. The role of PKC in desensitization was also studied. Prior exposure to PAF also desensitized the increase in membrane PKC activity evoked by a single concentration of PAF. However, when the PAF response was desensitized, PKC priming of the response to FMLP or PMA still occurred, suggesting that PKC activity may play a role in the maintenance of the primed state despite PAF desensitization. These data suggest that: (1) PAF priming is receptor- and PKC-mediated but is independent of pertussis toxin-inhibitable G-proteins or intracellular calcium, (2) during migration in vivo, neutrophils may be desensitized to the direct effects of PAF but maintain the capacity for enhanced responses to other stimuli, (3) desensitization of PAF-induced particulate PKC activity also occurs, but PAF primes PKC activity despite PAF desensitization, and (4) distinct mechanisms govern the direct and priming effects of PAF on oxidative metabolism. © 1993 Wiley-Liss, Inc.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcp.1041560125
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