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  • Life and Medical Sciences  (73)
  • Biochemistry and Biotechnology  (8)
  • SPACE SCIENCES
  • Humans
  • Lunar and Planetary Science and Exploration
  • ASTROPHYSICS
  • 1955-1959  (48)
  • 1930-1934  (33)
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  • 1
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    Journal of Morphology 53 (1932), S. 189-199 
    ISSN: 0362-2525
    Schlagwort(e): Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Notizen: This paper describes ultraviolet (λ = 2750 A) photomicrographs of resting and dividing chicken macrophages and fibroblasts and of erythrocytes and lymphocytes. The structures found in these photographs are compared with the ones brought out in fixed material by Feulgen staining and found to be essentially similar in appearance. A preliminary series of ultraviolet pictures is also shown of a single fibroblast passing through several of its stages of division.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 2
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    Journal of Morphology 54 (1933), S. 477-491 
    ISSN: 0362-2525
    Schlagwort(e): Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Notizen: The mitochondria in the male germ cells of Sciara exhibit peculiarities as regards both morphological characteristics and distribution. In form. they show superficial similarity with those of some of the scorpions, while their distribution may be peculiar to the genus and depend on unusual meiotic divisions.
    Zusätzliches Material: 4 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 3
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    Journal of Morphology 55 (1933), S. 207-251 
    ISSN: 0362-2525
    Schlagwort(e): Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Notizen: The Goodeidae are a family of cyprinodonts containing about nine genera and twenty-six species. They are confined exclusively to the Mexican Plateau and to streams in the immediate vicinity. All are viviparous. Fertilization is internal. The eggs are extremely small and contain very little yolk. The embryos are retained in the ovarian follicles until the yolk is practically absorbed, in the meantime developing unique absorptive organs in the form of extensive ribbon-shaped proctodaeal processes. The embryos are evacuated into the intra-ovarian cavity where they are retained for several weeks, during which time the proctodaeal processes become extended. The ovary becomes a nutritive organ and produces secretions which are discharged into the intra-ovarian cavity and absorbed by the embryo through their unique processes. The processes differ in form, number, and histological structure, but are specific in their peculiarities for each species. These specific differences, together with marked differences in the ovary, will furnish a basis for a re-classification of the genera and species of the family. A comparison in made between this family and the other ovo-viviparous and viviparous cyprinodonts, on the basis of which it is concluded that the Goodeidae have arisen separately from an ovo-viviparous ancestor, which in turn was derived from an ovo-viviparous type. A comparison is also made between the peculiarities of reproduction in this family and those of other viviparous teleosts.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 4
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    Journal of Morphology 56 (1934), S. 325-337 
    ISSN: 0362-2525
    Schlagwort(e): Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Notizen: The purpose of this study was to learn something of the nature of the bead-like bodies which occur in the head of the sperm of the fowl since it was found in a previous study that they are apparently affected in a characteristic manner by vitamin E deficiency.Staining tests indicate that these bodies are composed of fats and fatty acids since they respond to osmic acid and Nile blue sulphate. They are also impregnated with silver nitrate and hence may be associated with the so-called Golgi materials of the cell.The beads first appear as a complete single row but subsequently they undergo fragmentation and redistribution. The whole process is probably a final transitory step in sperm transformation.The presence of this fatty material may signify that the sperm of the fowl, in contrast to that of most other animals, carries a store of food material to support its activity after liberation. The sperm may also be the carrier of a definite amount of vitamin E. Furthermore, the presence of this material may offer an explanation of the high resistance of the testis of the fowl to vitamin E deficiency because, since this vitamin is fat soluble, the testis as a whole would probably receive a disproportionately large share of the vitamin E stores of the individual.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 5
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    Journal of Morphology 55 (1934), S. 577-609 
    ISSN: 0362-2525
    Schlagwort(e): Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Notizen: An investigation has been conducted to ascertain the relationship of certain structures in the embryo of the grasshopper known as Melanoplus differentialis with reproductive organs in the adult male.The order of development of these structures was traced through the entire life history.It was determined that they are the rudiments of certain reproductive organs and that the knowledge obtained serves as an aid in more accurately classifying insects.
    Zusätzliches Material: 1 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 6
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    Journal of Morphology 102 (1958), S. 91-117 
    ISSN: 0362-2525
    Schlagwort(e): Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Zusätzliches Material: 1 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 7
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    Journal of Morphology 52 (1931), S. 593-607 
    ISSN: 0362-2525
    Schlagwort(e): Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Notizen: This study is concerned with the interrelationship existing among the polymorphie soldier castes of six representative subgenera of the genus Nasutitermes. By measurements of anatomical parts and camera-lucida drawings, an attempt has been made to compare these particular subgenera on a basis of gradual divergence of certain structures. For this purpose a series of tables was compiled in which apparently unstable structures were compared to a relatively stable figure in all available species of the selected subgenera.According to my findings, it was concluded that there is no strict correspondence between the major, intermediate, and minor castes of different subgenera of the genus Nasutitermes. Particular reference is made to the work of N. Holmgren ('12) and to that of J. S. Huxley on heterogonic growth.
    Zusätzliches Material: 4 Tab.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 8
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    Journal of Morphology 50 (1930), S. 517-525 
    ISSN: 0362-2525
    Schlagwort(e): Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Notizen: The fertilized hen's eggs of known origin were incubated under predetermined, standardized, and uniform conditions of all physical factors except air, the composition of which in respect to the carbon dioxide and oxygen varied in each experiment. The growth and mortality of the embryo were studied daily, with, on an average, four observations.The experimental data show that the continuous exposure to about 0.4 per cent of carbon dioxide in the air of the incubator stimulated growth during the first part of embryonic life. A high content of carbon dioxide and at the same time a slightly reduced content of oxygen resulted in diminishing of the size and increasing of mortality of the embryo. The maximum combined proportions of these gases possible for growth of the embryo were about 22.0 and 16.3 per cent, respectively. A temporary exposure (twenty-four and forty-eight hours) to a large amount of carbon dioxide resulted in diminishing the size of the embryo without apparent deformities or increase of mortality.
    Zusätzliches Material: 3 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 9
    ISSN: 0362-2525
    Schlagwort(e): Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Notizen: Histological studies of testes of both immature and mature individuals show that the peritoneal epithelium does not give up its proliferative capacities with the completion of testis differentiation. Certain regions of the antimesorchial surface retain their activity and continue to contribute cellular elements during testis growth. Stromal cells, germ cells, and sections of or entire seminiferous tubules originate from the peritoneum in the form of cord-like ingrowths. In this form, the proliferations of the germinal epithelium of the testes are similar to and homologous with the continuous proliferations of the germinal epithelium of the ovary.In Sternotherus, both testis and ovary differentiate out of a bisexual primordium in which the deeper parts of the germinal epithelium form an ovarian cortex. Since the germinal epithelium persists as an active part of both ovary and testis, it must be responsive to the same physiological factors of female or male differentiation respectively. It is indifferent sexually and once the direction of sex differentiation is established, the response of the germinal epithelium is in the determined direction. Its activity is then to produce either seminiferous tubules or ovarian follicles, and is directly dependent upon the processes of embryonic sex differentiation and determination.
    Zusätzliches Material: 1 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 10
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    Journal of Morphology 56 (1934), S. 339-359 
    ISSN: 0362-2525
    Schlagwort(e): Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Notizen: The effects of vitamin E deficiency in the fowl were observed in Rhode Island Red males over a period of approximately 2 years.Mating experiments showed that after 1 year on the E-free diet all of the males were capable of fertilizing ova, but that after 2 years some of the males were sterile.Sperm smears showed that shortly after the beginning of the experiment, many of the mature spermatozoa exhibited an abnormal condition of the nuclear material of the head, while others remained normal.In histological sections of the testes made at the end of the 2 years, conditions varied from almost normal to complete atrophy, the latter being a condition that has already been described in the male mammal. Moreover, the conditions in any given section were not uniform for even in an advanced stage of E deficiency there were small islands of apparently normal tissue. However, in this case, as in the mammal, the process of degeneration affects the mature sperm cells first and gradually works to the outside of the seminiferous tubule thus attacking the youngest maturation stages last.The results of the experiment point definitely to destruction of the testis under prolonged E-deficient conditions but it is also quite apparent that the testis of the fowl is extremely resistant to vitamin E deficiency.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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