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  • 1
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: A study of the integument of the aquatic mite Arrenurus major Marshall is presented. When the cuticle is examined with the unaided eye and the light microscope, it appears to possess numerous tiny pits. However, scanning electron micrographs of the cuticle reveal that it is a solid surface with topographical sculpturing of the epicuticle, indicating that the “pits” are an internal phenomenon. In cuticle which has been sectioned, areas devoid of cuticular material beneath the thin exocuticle are revealed. These areas are the pits which are goblet-shaped.The integument consists of five major strata. These are from the outside to the inside: (1) a superficial layer with a maximum observed thickness of 725 Å, (2) an epicuticle with a thickness of about 900 Å and composed of at least four sublayers, (3) an exocuticle with a thickness of about 1.5 Å. Fibers of the exocuticle are arranged in a Bouligand pattern and exhibit a regularly occurring discontinuity with a spacing of 200 Å. (4) An endocuticle ranging from 15 to 20 μ in thickness. The endocuticle is characterized by bandings which superficially resemble the lamellae of insects but are not homologous, microfibers which exhibit a preferred orientation, and the presence of the pits; and (5) an epidermis lying beneath the endocuticle and extending into the pits.Pore canals are present only in the exocuticle and have their origin at the apices of the pits. The pore canals contain a central filament, and a plug is present just beneath the epicuticle.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal of Morphology 140 (1973), S. 461-465 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The development of electric organ spindles of Gymnarchus niloticus has been investigated with respect to the exact time and place of origin and the process of formation of the adult plan. The results are compared with those of Dahlgren ('14). A common primordium for all the electroplates of of a spindle as held by Dahlgren ('14) is not supported by the present work.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 0002-9106
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: Utilizing immunohistochemistry with rabbit antiserum to synthetic luteinizing hormone-releasing hormone (LRH), LRH was localized in the peripheral region of the median eminence in the mouse and rat, and more generally in the median eminence of the guinea pig.
    Additional Material: 5 Ill.
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  • 4
    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
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  • 5
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The development of the electric organs of Gymnarchus niloticus has been studied and the origin and histogenesis of an electroplate worked out. A segmental origin of the electroplate is reported for the first time for this fish. Light has been thrown on many hitherto obscure phenomena, viz., growth of core girth, loss of transverse striations on the myofibrillar elements, differentiation of electroplate polarities, shortening in length of the electroplate etc. The transverse striations of the myofibrillar bundle of the electroplate primordium progressively disappear with development owing to splitting apart of the constituent myofilaments and consequent loss of their parallel order, and not to degeneration of the myofibrillar bundle. The excessive growth of the core girth of the electroplates is caused by the deposition of some kind of interfibrillar substance probably secreted by the peripheral cytoplasm.
    Additional Material: 14 Ill.
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  • 6
    ISSN: 0003-276X
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: Alkaline phosphatase (AlPase) has been examined histochemically and biochemically in Swiss White (SW) mouse and Sprague-Dawley (SD) rat embryos during comparable stages of secondary palatal development. In the rats, AlPase was not detectable histochemically until after shelf transposition. Enzyme activity by biochemical assay was low in stages before shelf elevation. The mice, in contrast, showed AlPase in posterior areas of the developing shelves soon after shelf formation by histochemical techniques. With biochemical assays AlPase was higher in mouse than in rat shelves in early stages. After shelf transposition AlPase activity in the rat approached AlPase activity in the mouse by biochemical assays, but was demonstrable only in the posterior areas of the secondary palate by histochemical techniques.
    Additional Material: 1 Ill.
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  • 7
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Rabbit muscle aldolase in situ appears to undergo several modification reactions. One of these, specific deamidation of an asparagine residue near the COOH-terminus, appears to account for the presence of two types of subunits in the enzyme isolated from the muscle of adult rabbits. Evidence for a second modification is the presence of approximately one equivalent of organic phosphorus in the crystalline enzyme preparations. The presence of this phosphate group may be related to the incomplete release of COOH-terminal tyrosine residues from the enzyme protein with carboxypeptidase. Two reactions with substrate, both leading to the incorporation of organic phosphorus, have been demonstrated in vitro. A reaction with glyceraldehyde 3-phosphate or erythrose 4-phosphate leads to loss of catalytic activity and change in the susceptibility of COOH-terminus to carboxypeptidase. The other reaction, with fructose 1,6-diphosphate at low concentration, does not affect the activity of the enzyme, nor its susceptibility towards the action of carboxypeptidase. Either or both of these may be related to the changes which appear to occur during the life of the enzyme in vivo.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
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  • 8
    ISSN: 0003-276X
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: The objective was to study the fate of specific secretory cell types of the rat hypophysis when grown in primary monolayer cultures for periods ranging up to 32 days. The cells were identified immunohistochemically using peroxidase-labeled antibody. Early in the culture period TSH-cells were scarce and by 12 days they could no longer be identified. In most cultures LH-cells were well stained and common for eight to 12 days, after which they underwent involution. Growth hormone cells were a prominent feature up to six days but by 12 days they were declining in number, size, and stainability; in contrast, prolactin cells proliferated and were large and intensely stained throughout the period of study, ultimately becoming the dominant secretory cell type. Corticotropic cells also continued throughout the period of study without regression. Thus drastic shifts occur with time in the relative proportions of cell types in monolayer cultures of rat pituitary cells.
    Additional Material: 1 Ill.
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  • 9
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    American Journal of Anatomy 141 (1974), S. 415-426 
    ISSN: 0002-9106
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: Nineteen linear and three angular dimensions were measured for 590 left femurs derived from Bronze-Age to present-day population samples. Univariate analysis showed varying patterns of contrast between the populations, depending upon which femoral dimension was compared. Similarly, multivariate analysis also provided varying patterns of contrast between the populations, depending upon which group of dimensions was included in the analysis. Following standardization of the femoral linear dimensions against the maximum femoral length, in contrast, repeat multivariate analyses showed a progression from the Bronze-Age to the present-day samples, although there was only limited discrimination between the samples.
    Additional Material: 8 Ill.
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  • 10
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    American Journal of Anatomy 136 (1973), S. 259-263 
    ISSN: 0002-9106
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: Overall height, arm length, leg length and mandibular size were measured in 800 male subjects from three ethnic groups aged three months to 20 years. Mandibular size or limb size showed a linear relationship when plotted against overall body height for each ethnic group and emphasized that different relationships exist between the size of a region and that of the body as a whole in caucasoids, negroids and mongoloids.
    Additional Material: 1 Tab.
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