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  • 1
    Digitale Medien
    Digitale Medien
    Oxford, UK : Blackwell Publishing Ltd
    Annals of the New York Academy of Sciences 642 (1991), S. 0 
    ISSN: 1749-6632
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Allgemeine Naturwissenschaft
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 2
    Digitale Medien
    Digitale Medien
    Oxford, UK : Blackwell Publishing Ltd
    Annals of the New York Academy of Sciences 642 (1991), S. 0 
    ISSN: 1749-6632
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Allgemeine Naturwissenschaft
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 3
    Digitale Medien
    Digitale Medien
    Oxford, UK : Blackwell Publishing Ltd
    Journal of cutaneous pathology 17 (1990), S. 0 
    ISSN: 1600-0560
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Medizin
    Notizen: The prime diagnostic feature of acute alopecia areata is the presence of exclamation mark hairs. These characteristic hairs fracture at their distal end and taper proximally towards the scalp, giving them the appearance of an exclamation mark. Hair morphology was studied in 8 patients with untreated acute alopecia areata and 3 normal adults without hair loss. Light microscopy, transmission and scanning electron microscopy revealed distinct structural differences in the distal end of hairs compared with the remainder of their length and with normal hair shafts. Transverse sections of hairs just below the frayed brush-like tip often displayed asymmetrical cortex disintegration. One side was compact and homogeneous while the other was deeply fissured and/or broken up into discrete heterogeneous-staining fragments of cortical, stratum corneum and cuticular components in addition to apparently degenerate cortex. Many exclamation mark hair tips lacked cuticle and had irregular profiles. Melanin was found in cortical and medullary fragments at the tip, although it was absent in the more degenerate forms of cortex. More proximal sections of these pathognomic telogen hairs revealed nearly normal hair shaft ultrastructure.
    Materialart: Digitale Medien
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  • 4
    Digitale Medien
    Digitale Medien
    Oxford, UK : Blackwell Publishing Ltd
    British journal of dermatology 119 (1988), S. 0 
    ISSN: 1365-2133
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Medizin
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 5
    Digitale Medien
    Digitale Medien
    [s.l.] : Nature Publishing Group
    Nature 304 (1983), S. 633-635 
    ISSN: 1476-4687
    Quelle: Nature Archives 1869 - 2009
    Thema: Biologie , Chemie und Pharmazie , Medizin , Allgemeine Naturwissenschaft , Physik
    Notizen: [Auszug] Previous studies have shown that many animals accumulate high concentrations of toxic metals1-5. Some animals are polluted with metals from anthropogenic sources, while others appear to be contaminated from natural sources. On the basis of broad ecological judgements (for example, apparent breeding ...
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 6
    Digitale Medien
    Digitale Medien
    [s.l.] : Nature Publishing Group
    Nature 249 (1974), S. 366-367 
    ISSN: 1476-4687
    Quelle: Nature Archives 1869 - 2009
    Thema: Biologie , Chemie und Pharmazie , Medizin , Allgemeine Naturwissenschaft , Physik
    Notizen: [Auszug] In Quelea quelea, as in other birds1, the thymus consists of a number of lobes well separated from one another in two long chains one on each side of the neck. In embryos about to hatch each lobe was found to be small (less than 1 mm long) and white; but by the age of 10 d, 17 out of 60 individuals ...
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 7
    Digitale Medien
    Digitale Medien
    Springer
    Cell & tissue research 109 (1970), S. 112-137 
    ISSN: 1432-0878
    Schlagwort(e): Tarsi ; Locusts ; Schistocerca gregaria Forskål ; Structure
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary The tarsus of S. gregaria is divided into three units (here called segments) and an arolium set between a pair of claws. The first segment bears three pairs of pulvilli in the fore and middle legs, and one pair and two single pulvilli in the hind legs. Segment two bears a pair of pulvilli, segment three one long pulvillus and the arolium a similar pad on the undersurface. The outer layers of the arolium pad differ from those of the pulvilli in possibly lacking an epicuticle and in having a layer of cuticle which, unlike the corresponding layer in the pulvilli, does not stain with protein stains. The claws and dorsal surfaces bear trichoid sensilla, basiconic sensilla and campaniform sensilla. Smaller basiconic sensilla and canal sensilla occur on the proximal part of the pulvilli, and basiconic sensilla on the arolium undersurface. Internally the cuticle is modified in the arolium and pulvilli so that rods of probably chitin and resilin are formed. This would impart flexibility to the undersurfaces whilst retaining some degree of rigidity which might prevent damage to the small and delicate sense organs on the pulvilli. The tip of the arolium is specialised for adhesion, and there are two large neurones internally which could conceivably monitor attachment or detachment of the tip. There are chordotonal organs in segment three, and several other large neurones throughout the tarsus, some of which are associated with the slings of tissue holding the apodeme in a ventral position. Gland cells occurring in the dorsal epidermis of the adult mature male are also briefly described.
    Materialart: Digitale Medien
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  • 8
    Digitale Medien
    Digitale Medien
    Springer
    Cell & tissue research 164 (1975), S. 233-249 
    ISSN: 1432-0878
    Schlagwort(e): Thymus ; Lymphocytes ; Pyknotic cells ; Erythrocytes ; Nuclear morphometrics
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary The cortex of the thymus glands of embryos, chicks, juveniles, fledglings and adults from several colonies of Quelea quelea were studied using an image analyser (Quantimet 720) to determine cell populations and nuclear sizes. Just prior to hatching the lobes showed a high level of mitosis and consisted of predominantly small lymphocytes. The larger glands of chicks and juveniles had higher cell populations; pyknotic cells and erythrocytes occurred free in the cortex. The lobes of adults were more variable but in general mitosis occurred in enlarging glands of adults from colonies with eggs; most lobes contained pyknotic cells but not in such high numbers as in lobes from chicks and fledglings. Erythrocytes were common, occurring in large numbers in the cortex in some birds. The factors affecting the interpretation of these data are discussed in detail.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 9
    Digitale Medien
    Digitale Medien
    Springer
    Cell & tissue research 237 (1984), S. 227-237 
    ISSN: 1432-0878
    Schlagwort(e): Thymus ; Epithelial cells ; Hassall's ; Man
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary To evaluate interrelationships among epithelial cells, and between morphology and function in the microenvironment, we studied the ultrastructural morphology of epithelial cells in sections of human thymus from donors aged 2 months to 31 years. Six types of epithelial cells were observed: “subcapsular-perivascular” (type 1); “pale” (type 2); “intermediate” (type 3); “dark” (type 4); “undifferentiated” (type 5); and “large-medullary” (type 6). Cells of types 2, 3 and 4 were found throughout the organ. The type-2 to -4 epithelial cells may represent various stages in a differentiation process. In this, type-2 cells are very active and type-4 cells are possibly degenerating elements. Type-4 cells can also contribute to Hassall's corpuscles. Type-5 cells were located mainly in the cortico-medullary region and showed the morphological characteristics of undifferentiated elements. Type-6 cells were located exclusively in the medulla and displayed characteristics of cellular activity. Small Hassall's corpuscles consisted of type-6 epithelial cells; in larger corpuscles many nuclei of type-6 cells were found. Cells of types 2 and 6 contained tubular structures (diameter approximately 20 nm). Concerning the function of thymus epithelial cells, the features associated with protein synthesis observed in cellular types 2 and 6 make them likely candidates for humoral factor-producing and/or secreting elements. In addition, type-2 and -3 cells in the cortex appear to contribute to a special pattern of epithelium-lymphocyte interaction (“thymic nurse cells”), as demonstrated by the intracytoplasmic location of lymphocytes in the epithelial cells. The various steps in intrathymic T-cell maturation occur at locations in a microenvironment composed of morphologically distinct epithelial cells.
    Materialart: Digitale Medien
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  • 10
    Digitale Medien
    Digitale Medien
    Springer
    Cell & tissue research 199 (1979), S. 37-61 
    ISSN: 1432-0878
    Schlagwort(e): Avian thymus ; Ultrastructure ; Erythropoiesis
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary Thymus lobes from three species of birds, Quelea quelea, Passer domesticus and Sturnus vulgaris, have been examined ultrastructurally. The component cell types are compared with their counterparts in mammalian thymus glands, and found to be similar. Greater differences exist between small, intermediate and enlarged lobes of one species than exist between species. Developing erythroid cells are present in most enlarging and some enlarged glands. They appear to be developing at the expense of lymphoid cells in some birds. The origin of these cells is discussed. Cells that are possible candidates for the production of some thymic hormones are also described.
    Materialart: Digitale Medien
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