Browsing by Subject "Median eminence"

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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 circumventricular organs
    (Universidad de Murcia. Departamento de Biología Celular e Histología, 2017) Kaur, Charanjit; Ling, Eng Ang
    The circumventricular organs (CVOs) are midline structures located around the third and fourth ventricles that are characterized by a lack of blood-brain barrier. The pineal gland, median eminence, neurohypophysis and the subcommisural organ are classified as secretory, whereas the subfornical organ, area postrema and the organum vasculosum of the lamina terminalis as the sensory CVOs. Glial cells consisting of astrocytes and microglia/macrophages are present in all these organs. The pineal gland, neurohypophysis and the median eminence lack the presence of neurons that are present in the rest of the CVOs. Most of the CVOs are lined by ependymal cells except for the pineal and the neurohypophysis. Modified ependymal cells known as tanycytes are present in the ependymal lining. These organs are important sites for communication with the cerebrospinal fluid as well as between the brain and peripheral organs via blood-borne products as they lack the blood-brain barrier.