Differential endometrial gene expression in pregnant and non-pregnant sows

In an attempt to unveil part of the molecular processes controlling porcine placentation we have investigated the pregnancy induced gene expression in the porcine endometrium at Day 14 after insemination using the Affymetrix GeneChip® Porcine Genome Array. At Day 14 after insemination, samples were obtained from the endometrium of pregnant sows and sows inseminated with inactivated semen for RNA extraction and hybridization on Affymetrix microarrays. The uteri were removed and each uterine horn was flushed with PBS containing 1% fetal calf serum, and subsequently opened longitudinally at the anti-mesometrial side. The sites of embryonic attachment were macroscopically visual in the endometrium on the mesometrial side in form of hyperemic zones. Samples of the endometrium (lamina epithelialis, lamina propria and tela submucosa, but not tunica muscularis) were isolated from proximal (the end close to the ovaries), intermedial, and distal (next to the corpus uteri)) sections of each uterine horn. Samples were taken from the endometrium of the non-pregnant animals at comparable locations.