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  • 1
    ISSN: 1432-0878
    Schlagwort(e): Adrenal cortex ; Corticosterone ; Autoradiography ; Morphometry
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary The effects of corticosterone on adrenocortical cells of intact and hypophysectomized ACTH-treated rats were investigated by morphometric and autoradiographic methods. The data obtained in these experiments allow us to make the following conclusions: 1 The most important morphological parameter for assessing the activity of a steroid-secreting cell is the quantity of smooth endoplasmic reticulum. 2 The decrement in the smooth reticulum in adrenocortical cells of rats treated with corticosterone is due to an inhibition of the protein synthesis by the hormones themselves. 3 There is in vivo a direct negative feed-back control mechanism at the adrenal level, mediated by an inhibition of the RNA synthesis by the corticosteroid-hormones. 4 The trophism of the mitochondrial fraction of adrenocortical cells is controlled by ACTH. It is possible to hypothesize that ACTH intervenes in the regulation of the mitochondrial RNA and DNA synthesis.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 2
    Digitale Medien
    Digitale Medien
    Springer
    Cell & tissue research 118 (1971), S. 35-48 
    ISSN: 1432-0878
    Schlagwort(e): Adrenal cortex ; ACTH ; Mitochondria ; RNA synthesis ; Autoradiography
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary The incorporation of 3H-thymidine and 3H-uridine into adrenocortical cells of intact and ACTH-treated rats was investigated by high-resolution autoradiography. The quantitative analysis of autoradiographs shows no effect of ACTH on the incorporation of 3H-thymidine, at least in our experimental conditions. On the contrary, ACTH was found to enhance the incorporation of 3H-uridine into both adrenocortical nuclei and mitochondria. These findings are discussed in relation to numerous biochemical and morphological data, indicating that ACTH stimulates the synthesis of enzymes and structural proteins of adrenocortical cells. It is suggested that the mechanism of action of ACTH on adrenal cortex, consists in an integrated stimulation of both nuclear and mitochondrial DNA-dependent RNA synthesis.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 3
    Digitale Medien
    Digitale Medien
    Springer
    Cell & tissue research 106 (1970), S. 143-154 
    ISSN: 1432-0878
    Schlagwort(e): Adrenal cortex ; Corticosteroid-hormones ; Smooth endoplasmic reticulum ; Stereology
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary The ultrastructural changes occuring in adrenocortical cells of prednisolone-treated rats were evaluated by morphometric methods. They consist mostly in a conspicuous decrease in the smooth reticulum surface and in the lipid droplets. The diminution of the smooth reticulum accounts for about 60 % of the decrement in cellular volume and in adrenal weight. Since numerous enzymes of corticosteroid-synthesis are localized in the microsomal fraction of adrenocortical cells, it is reasonable to suggest that the decrement of these organelles is the morphological expression of the cellular deficit in hormone-synthesis. The possible mechanism of reduction of the reticulum membranes is discussed in relation to the probable regulation mechanism of the adrenocortical secretion. It is proposed that the reticulum decrement is the result of a reduced synthesis of new membranes, due to an inhibition of protein-synthesis in adrenocortical cells.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 4
    ISSN: 1432-0878
    Schlagwort(e): Rats ; Radioautography ; Cholesterol-3H ; Steroids (biosynthesis) ; Adrenal glands
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary In the zona reticularis of the rat adrenal cortex three types of cells are to be observed: light, dark, and very dark cells. A time study of the incorporation of cholesterol-3H into these elements has been made. The data obtained from autoradiographic study are discussed in relation to the hypothesis that the light cells are elements in active steroido-synthesis, the dark cells are resting elements, and the very dark cells are elements in degeneration.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 5
    Digitale Medien
    Digitale Medien
    Springer
    Cell & tissue research 103 (1970), S. 382-397 
    ISSN: 1432-0878
    Schlagwort(e): Adrenal cortex ; Newborn rat ; Stereology ; Electron microscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary The structure of the zona glomerulosa and the zona fasciculata of the newborn rat adrenal cortex has been studied by the light and the electron microscope. The ultrastructural features of the cells of both zones are described. By morphometric methods the relative volumes occupied by mitochondria and by lipid droplets have been evaluated. The “membrane profile concentration” (i.e. the average number of microns of smooth reticulum profiles per square micron of cytoplasm) has been also measured. The most significant ultrastructural differences between the cells of the two zones concern the mitochondria, the lipid droplets, and the smooth endoplasmic reticulum. The mitochondria show typical lamellar cristae in the elements of the zona glomerulosa, and vesicular cristae in the cells of the zona fasciculata. They occupy the same relative volume in both elements. The lipid droplets and the smooth reticulum show no qualitative differences in the two cell types, but they are found in a larger amount in the cells of the zona fasciculata. These ultrastructural findings are discussed in relation to the numerous biochemical data, suggesting that the cells of the zona glomerulosa are resting elements at birth, while the cells of the zona fasciculata are active steroid-secreting elements already in late gestation.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 6
    Digitale Medien
    Digitale Medien
    Springer
    Cell & tissue research 103 (1970), S. 398-409 
    ISSN: 1432-0878
    Schlagwort(e): Adrenal cortex ; Newborn rat ; Electron microscopy ; Lysosomes
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary The structural changes of the zona juxtamedullaris of the rat adrenal cortex at birth, have been examined by the light and the electron microscope. In this zone clusters of medullary cells lying among the strands of cortical tissue were observed. In the inner portion of the zona juxtamedullaris two types of adrenocortical cells were found: light and very-dark cells. The latter are smaller than the light cells and are always in close connection with the medullary tissue. The ultrastructural features of the very-dark cells suggest that these elements are in degeneration. This finding supports the hypothesis that at birth there is a partial degeneration of the rat zona juxtamedullaris, i.e. the zone corresponding to the “fetal zone” of some mammalian species. It is proposed that in all mammalian species at birth there is a partial regression of the zona juxtamedullaris and that the regression of the “fetal zone” is only the quantitative increase of this phenomenon. This hypothesis is discussed in relation to numerous data demonstrating that there are enzymatic conditions in the rat during fetal life, which permit a discrete hypertrophy of the adrenal cortex.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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