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Gene expression profiles of cumulus cell oocyte complexes (COCs) during ovulation reveal cumulus cells express neuronal and immune-related genes: Does this expand their role in the ovulation process
Hernandez-Gonzalez I, et al ?
Ovulation is a complex process initiated by the preovulatory LH surge, characterized by cumulus oocyte complex (COC) expansion and completed by the release of a mature oocyte. Although many ovarian genes that impact ovulation have been identified, we hypothesized that genes selectively expressed in COCs would be overlooked by approaches using whole ovary or granulosa cell samples. RNA isolated from COCs collected from preovulatory follicles of eCG-primed mice and at selected times following hCG treatment was subjected to microarray analyses and results confirmed by RT-PCR analyses, Western blotting and immunofluorescent studies. A remarkable number of genes was up-regulated in COCs including Areg, Ereg, and Btc. Several genes selectively expressed in cumulus cells compared with granulosa cells were related to neuronal (Mbp, Tnc, Nts) or immune (Alcam, Pdcd1, Cd34, Cd52 and Cxcr4) cell function. In addition to Sfrp2, other members of the Wnt/Fzd family (Sfrp4, Fdz1 and Fdz2) were expressed in COCs. Thus, there is a cumulus cell-specific, terminal differentiation process. Furthermore, immunofluorescent analyses documented that cumulus cells are highly mitotic for 4-8 h after hCG and then cease dividing in association with reduced levels of Ccnd2 mRNA. Other down-regulated genes included: Cyp19a1, Fshr, Inhb, and the oocyte factors Zp1-3 and Gja4. In summary, the vast number of matrix, neuronal and especially immune cell-related genes identified by the gene profiling data of COCs constitutes strong and novel evidence that cumulus cells possess a repertoire of immune functions that could be far greater than simply mediating an inflammatory-like response.
Kusamura S, et al reported the expression of p53, c-erbB-2, Ki-67, and CD34 in granulosa cell tumor of the
ovary.
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Identification of CD133-, CD34- and KDR-positive cells in the bovine ovary: a new site of vascular wall resident endothelial progenitor cells. Schoen K et al. Intense angiogenesis, vascular remodelling as well as regression of its vasculature are prerequisites for ovarian function with its cyclically developing and regressing follicles and corpora lutea. So far neither a stringent explanation for the enormous angiogenic potential of the ovary nor its cellular origins have been suggested. In an earlier study of our work group, endothelial cells were isolated from the bovine corpus luteum and cultivatedin vitro. They performed vasulogenesis in vitro and showed properties of progenitor cells. The present study aimed at in situ identification of endothelial progenitor cells (EPCs) in the bovine ovary. Immunohistochemical examinations, based on the detection of KDR- and CD34-co-labelled cells - a marker combination that amongst othersis commonly accepted as typical for EPC identification - were performed. Hormonal cycle dependent expression varieties were analysed by the measurement of mRNA amounts of CD34 and KDR as well as the stem cell marker CD133 (Prominin 1). Ovarian samples comprising corpora lutea of varying stages (developing and mature corpus luteum, corpus luteum in regression, corpus luteum of pregnancy) from 17 adult cows were examined. Results show that specific mRNA of CD133, CD34 and KDR was expressed in ovaries of all luteal stages. Expression data analysis revealed significant differences in CD133 and CD34 expression levels between the luteal stages but no significant differences in KDR expression. CD34/KDR co-immunoreactive cells were predominantly situated within the media of arterial vessel wall. The detection of ovarian EPCs represents an important step towards further understanding of the mechanisms involved in the reproductive biology and pathophysiology of the ovary.
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