Browsing by Subject "Hypophysectomy"

Now showing 1 - 3 of 3
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    Characterization of GFAP expression and cell proliferation in the rat median eminence following hypophysectomy
    (F. Hernández y Juan F. Madrid. Universidad de Murcia: Departamento de Biología Celular e Histología, 2001) Vázquez, R.; Blanco, E.; Sánchez, F.; Juanes, J. A.; Rubio, M.; Santos, M.; Vázquez, G.; Hernández, E.; Riesco, J. M.; Carretero, J.
    To analyze whether the reorganization of the rat medi an emin ence aft er hypophysectomy might be related to changes in gli al fibrill ary ac idi c protein (GFAP)- and cellular prolife ration, th e distribution of cells immunoreactive for GFAP and the prolife ration rate of such cells were analyzed at 20, 40 and 60 days posthypoph ysec tomy. Fo r this stud y, four rostra -ca ud al regions of the medi an eminence we re diffe renti ated: the retroc hi as mati c, preinfundibul a r, infundi bul ar and postinfundibul ar regions. In each of these regions, three layers were studied: the ependymal, the internal and the ex tern al. At 20 and 40 days aft er hypoph ysec tomy, significant increases in ce llular proliferation affecting all three laye rs studi ed in th e pre infundi bul a r a nd infundibul ar regio ns we re fo und . At the same time po ints, in c reases in GFAP ex pr essio n we re a lso obse rved . Howeve r, a ft e r 60 days, GFA P a nd proliferative ce llular nuclear antigen (PCNA) expression dec reased. Although va ri ati ons of PCNA and GFA P levels were ev id ent, no coloca lisa ti on of PCNA and GFAP was fo und in the cells of the medi an eminence in untreated or hy pophysectomized rats when sections we re analyzed by double immunohistochemica l staining. Our results suggest that reorgani zation of med ian eminence in vo lves alt e rati o ns (o r modul ati o n) o f GFA Pimmunoreacti ve ce lls together with a proliferation of cells that are not GFAP-immunoreactive. This study also demonstrates that this reorgani zation is completed within the fi rst two months afte r hypophysectomy.
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    The effect of corticotropin-releasing hormone (CRH) on the adrenal medulla in hypophysectomized rats
    (Histology and histopathology, Vol.13, nº 1 (1998), 1998) Hoheisel, G.; Schauer, J.; Scherbaum, W. A.; Bornstein, S. R.
    CRH occurs in the adrenal medulla of rats. We were interested to know whether CRH affects medullary chromaffin cells in the absence of ACTH. We investigated the morphological changes of the adrenal medulla in Sprague Dawley rats with light and electron microscopy in normal rats, hypophysectomized rats, and hypophysectomized rats following injections of CRH (10 Jig = 3 nmol for three days). Chromaffin cells were characterized by immunohistochemistry (anti-tyrosine hydroxylase). At light microscopy level chromaffin cells of hypophysectomized rats were reduced in number. On electron microscopy the number of granules and cell organelles were decreased. Following injections of CRH the medulla regained a more compact texture with cell organelles homogenously distributed, but with chromaffin granules still being reduced in number. Immunohistochemistry allowed the identification of chromaffin cells located within the adrenal cortex. In hypophysectomized rats these cells showed fewer signs of alterations compared to cells located within the medulla itself and had recovered better after treatment with CRH. In conclusion. CRH seems to exert a trophic effect on chromaffin cells in the absence of pituitary ACTH. This observation may provide further evidence for a close interaction of the two neuroendocrine stress systems.
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    Ultrastructural study on the effects of hypophysectomy on the golden hamster parathyroid gland
    (Murcia : F. Hernández, 1991) Shoichi Emura; Shizuko Shoumura; Michiya Utsumi; Huayue Chen; Tomo Yamahira; Daisuke Ayakawa; Michio Arakawa; Hideo Isono
    The ultrastructure of the parathyroid glands of hypophysectomized golden hamsters was studied. In the parathyroid glands of hypophysectomized animals the Golgi complexes and secretory granules were significantly decreased and large vacuolar bodies were significantly increased compared with those of the control animals. In addition. the chief cells contained a few prosecretory granules in the Golgi areas and a few secretory granules were present in the peripheral cytoplasm. These results suggest that the synthesis and release of parathyroid hormone may be suppressed in the parathyroid glands of the hypophysectomized animals.