| dc.description.abstract |
The fallopian tube plays a central role in reproduction, providing the appropriate environmental conditions for oocyte maturation as well as for sperm capacitation. Furthermore, fertilization and the first cleavage stages of embryonic development take place in the oviduct. At the molecular level, only fragmentary data are available regarding the physiological changes in the oviduct epithelium during the estrous cycle. Therefore, we performed a systematic study of gene expression changes in bovine ipsilateral oviduct epithelial cells derived from either the ampulla or the isthmus part of the oviduct at four different time points of the estrous cycle. A cDNA array consisting of approximately 400 candidate genes, primarily identified in different studies in the context of gene expression regulation in the oviduct, was designed and hybridized with 33P-labeled cDNA probes prepared from 28 different tissue samples. These tissue samples were collected from cyclic Simmental heifers at Day 0 (n = 3), Day 3.5 (n = 3), Day 12 (n = 4) and Day 18 (n = 4) of the estrous cycle. Ipsilateral epithelial cells were separately collected from ampulla and isthmus. After array evaluation (AIDA Image Analyzer, version 3.41, Raytest, Straubenhardt, Germany), the raw data were normalized to internal reference cDNAs on the arrays. Statistical analysis was done using ANOVA and the Tukey post-hoc test (GeneSpring� version 6.1, Silicon Genetics, Redwood City, CA, USA). For selected genes, differential expression was verified by real-time RT-PCR. A simplified Gene Ontology was built for the genes present on the array and a pathway analysis was performed to elucidate gene networks involved in the regulation of oviduct epithelial cell function. The expression patterns of two functional groups of genes are presented here: genes that are related to immune functions and genes of the secretory pathway or encoding secreted proteins. Messenger-RNA levels of immune-related genes were higher in epithelial cells of the ampulla compared to the isthmus part of the oviduct. This implies that certain immune functions may be differentially regulated in ampulla and isthmus. Furthermore, mRNAs of genes of the secretory pathway showed highest levels mainly in the ampulla around time of estrus, which may be explained with the increase of the secretory activity in the epithelium of the ampulla beginning at pre-estrus. In general, this study shows the importance of a separate analysis of the oviduct compartments and the influence of the estrous cycle on the expression level of a variety of genes. In the context of fertilization and early embryo-maternal communication, these results could provide an insight into the physiological changes during the estrous cycle, which are the bases for these processes. This work was supported by the Deutsche Forschungsgemeinschaft (Research Unit ?Mechanisms of Embryo-Maternal Communication?; FOR 478/1). |
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