Browsing by Subject "Medulla"

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    3D Immunofluorescence analysis of early thymic morphogenesis and medulla development
    (F. Hernández y Juan F. Madrid. Universidad de Murcia: Departamento de Biología Celular e Histología, 2015) Muñoz, Juan José; Cejalvo, Teresa; Tobajas, Esther; Fanlo, Lucía; Cortés, Alfonso; Zapata, Agustín Gregorio
    The thymus represents an epithelial microenvironment specialized in the generation of Tcells. The mechanisms or signals that determine the initial differentiation of the two well distinguished histological compartments of the thymus, cortex and medulla, remain unknown. Here, we report a threedimensional analysis of the distribution of some established thymic epithelial markers in relation to thymic anatomical development during the first steps of thymus organogenesis. In the thymic primordium, initial lumen is lined by claudin (Cld)3/4+K5+ cells, after thymus growth and lobulation they form a continuous branched structure that increases its length and branching degree. Within it, the presence of luminal structures can be distinguished, even at E13.5. The medullary marker mouse thymic stroma 10 (MTS10) is upregulated in these Cld3/4+ lumen forming cells in a proximal-distal sequence. This structural organisation is histologically similar to that described in other epithelial organs undergoing a branching morphogenesis process. These results indicate that the thymic medulla can be evidenced as a continuous branched structure from early stages and suggest a thymic developmental program based on or containing elements of a branching morphogenesis program modified by the presence of lymphoid cells, in which medullary epithelial cell commitment is initially determined by lumen formation.
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    Ghrelin localization in the medulla of rat and human adrenal gland and in pheochromocytomas
    (Murcia : F. Hernández, 2008) Raghay, K.; Garcia-Caballero, Tomas; Bravo, S.; Alvárez, C.V.; González, R.; Diéguez, C.; Beiras, Andres; Fraga, M.; Gallego, R.
    Objective: Ghrelin is predominantly produced by neuroendocrine cells of stomach and has been expressed in several normal and tumour endocrine tissues. It has been reported that the localization of ghrelin is exclusively in the cortex of human and rat adrenal gland and in adrenocortical tumours. This prompted us to analyze the expression of this peptide in medulla of human and rat adrenal glands and in human pheochromocytomas. Design and methods: Analysis of ghrelin mRNA expression in rat adrenal gland was conducted by means of semi-quantitative RT-PCR. Ghrelin localization was studied in medulla of human and rat adrenal gland by immunohistochemistry. In addition, we have carried out a double immunofluorescence with chromogranin A to determine the specific cell type expressing ghrelin immunoreactivity. Ghrelin expression was also analyzed in five cases of pheochromocytoma by immunohistochemistry. Finally, Western blotting analysis was performed with goat ghrelin antibody in the cortex and in the medulla of rat adrenal gland. Results: RT-PCR demonstrated expression of ghrelin mRNA in rat adrenal gland. We also detected ghrelin expression in virtually all rat pheochromocytes by immunohistochemistry and double immunofluorescence. Furthermore, we showed ghrelin immunoreactivity in the medulla of human adrenal gland and in pheochromocytomas. By Western blotting, we found the expression of ghrelin precursor, proghrelin and mature ghrelin in the medulla of rat adrenals. However, the cortex of rat adrenal gland only expressed ghrelin precursor. Conclusions: Our study is the first to demonstrate a medullar expression of ghrelin in human and rat adrenal gland; we also showed ghrelin expression in pheochromocytomas.