Browsing by Subject "Ependyma"

Now showing 1 - 4 of 4
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    Autoradiographic localization of estrogen target cells in the spinal cord of the armadillo and baboon, a comparative study
    (Murcia : F. Hernández, 1987) Weaker, Frank J.; Sheridan, Peter J.
    The uptake and retention of radiolabeled estradiol by the spinal cord were examined in the baboon and the armadillo and compared to previous observations in the rat. Four females of each species were injected intracardially with 1.0-1.4 pg/kg body weight of %- estradiol and two females, one baboon and one armadillo, were injected with both labeled and 100-140 pg/kg body weight of unlabeled estradiol. One hour after the injections, the animals were killed and segments from the cervical, thoracic, lumbar and sacral cord were removed and processed for autoradiography. In the armadillo, labeling of neuronal nuclei were noted in laminae I & I1 and in alpha motor neurons. In addition, nuclei of the ependymal cells of the ventral portion of the central canal in the cervical cord concentrated radioactivity. In contrast, the baboon demonstrated only sporadic labeling of neurons in lamina I1 in all levels of the spinal cord. The comparison of our observations with that of the rat suggest that estrogen mediated sensations are probably coordinated at higher brain centers in the primate as opposed to the more primitive mammals
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    Combined TEM and SEM analysis of the rostral wall of the human III ventricle
    (Murcia : F. Hernández, 1993) Riesco, J. M.; Juanes, J.A.; Sánchez, F.; Blanco, E.; Carretero, J.; Maillo, A.; Vázquez, R.
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    Radial glia and cell debris removal during lesion-regeneration of the lizard medial cortex
    (Murcia : F. Hernández, 1999) Nacher, J.; Ramirez, C.; Palop, J.J.; Molowny, A.; Luis de la Iglesia, J.A.; López-García, Carlos
    Intraperitoneal injection of the neurotoxin 3- acetylpyridine (3AP) induces a rapid degeneration of the medial cerebral cortex (lizard fascia dentata) granular layer and of its zinc enriched axonal projection (lizard mossv fibres). After 6-8 weeks ~ost-lesionth e cell debris have ieen rekoved and the grakular layer is repopulated by neurons generated in the subjacent ependyma. Both processes, neuron incorporation and debris removal, seem to be crucial for successful regeneration. Scavenging processes in the lesioned mammalian CNS are usually carried out by microglia andlor astrocytes. In the lizard cerebral cortex there are no free astrocytes and the only glial fibrillary acid (GFAP) immunoreactive cells are radial glia-ependymocytes, similar to those present during mammalian CNS development. Ependymocytes, in addition to their help in vertical migrations of just generated immature neurons, built the cortical glial scaffold, insulate the blood capillaries, form the outer glial limiting membrane, thus playing an essential role in the lizard cortical blood-brain barrier. In this study, by means of GFAP-immunocytochemistry and electron microscopy, we have shown that radial glial cells participate actively in the removal/phagocytosis of cellular debris generated in the lesion process: mainly degenerated synapses, but interestingly, also some neuronal somata. Cell debris taken up by ependymocyte lateral processes seem to be progressively transported to either distal (pial) or proximal (ventricular) poles of the cell, where they result in lipofuscin accumulations. The hypothetical subsequent exchange of debris from ependymoglia by microglia/macrophages and Kolmer cells is discussed.
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    The ependymal surface of the fourth ventricle of the rat: a combined scanning and transmission electron microscopic study
    (Murcia : F. Hernández, 1992) Alvarez-Morujo, A.J.; Toranzo, D.; Blazquez, J.L.; Pelaez, B.; Sánchez, A.; Pastor, F.E.; Amat, G.; Amat, P.
    The morphological features of the ependymal surface and supraependymal elements of the fourth ventricle of the rat were examined by scanning electron microscopy (SEM) and by the transmission electron rnicroscopy (TEM). The results confirm the following aspects: 1) The presence of supraependymal elements and microvilli in the ependymal territories, including the sites where the cilia completely cover the ependymal surface; 2) The existence of cilia with oval or sphencal thickenings together with supraependymal bulbs similar in size to those of the larger ciliary swellings; 3) Identification of the long supraependymal fibres with intermittent fusiform dilations observed under the SEM with the neme fibres seen under the TEM; 4) The existence of intraventricular axodendritic synapses.