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  • 1
    ISSN: 1432-0878
    Keywords: Pituitary ; Mouse ; Pars intermedia ; Adrenoglomerulotropin ; Morphometric cytology
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Ultrastructural changes in the pars intermedia of the mouse pituitary caused by dietary sodium deprivation were investigated quantitatively. Of the six classes of organelles and inclusions selected for analysis in the pars intermedia cells, only the mitochondria showed no significant changes, while all of the remaining classes showed statistically significant changes. The most conspicuous changes were an abrupt decrease in the number of secretory granules and the appearance of parallel arrays of rough endoplasmic reticulum. The Golgi apparatus also showed hypertrophy accompanied by newly formed granules. The number of vesicles increased temporarily and then decreased. These findings indicate that dietary sodium depletion, a stimulus to greater aldosterone secretion, causes significant changes in the pars intermedia cells within 3 days, and these signs of hyperfunction last up to 5 days. The present study suggests a possible new role of the pars intermedia in the regulation of aldosterone secretion in response to dietary sodium deprivation in the mouse.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1432-0878
    Keywords: Pituitary ; Mouse ; Pars intermedia ; Adrenoglomerulotropin ; Morphometric cytology
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Fine structural alterations were investigated in cells of the pars intermedia of the pituitary of mice treated for four weeks with (a) a sodium deficient diet, (b) a sodium deficient diet mixed with propranolol (renininhibitor), (c) a sodium deficient diet combined with propranolol and aminoglutethimide (corticosterone 18-hydroxylase inhibitor), and (d) a sodium deficient diet combined with propranolol, aminoglutethimide and dexamethasone. The number of secretory granules decreased from 5.0/μm2 in the normal control to 2.4/μm2 in all four experimental groups suggesting that the cells in treated groups had reached an equilibrium in the production and release of secretory granules during the chronic treatments. The number of immature Golgi granules per unit Golgi area was 0.91 in the control, while this value rose to 3.29 (3.62 fold of the control), 4.37 (4.8 fold), 4.94 (5.43 fold) and 5.16 (5.67 fold) respectively in the four experimental groups. In these groups a good correlation was observed between the number of immature granules and the percent volume of rough endoplasmic reticulum (r=0.985, p〈0.01). The present study suggests that the pars intermedia contains an unidentified pituitary factor (or factors) essential for aldosterone biosynthesis.
    Type of Medium: Electronic Resource
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