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This Article Full Text Full Text (PDF) All Versions of this Article: 68/6/1951    most recent biolreprod.102.012948v1 Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Johnson, G. A. Articles by Gray, C. A. Search for Related Content PubMed PubMed Citation Articles by Johnson, G. A. Articles by Gray, C. A. Agricola Articles by Johnson, G. A. Articles by Gray, C. A.

Osteopontin Expression in Uterine Stroma Indicates a Decidualization-Like Differentiation During Ovine Pregnancy

Center for Animal Biotechnology and Genomics,² Department of Veterinary Anatomy and Public Health, College of Veterinary Medicine,³ Department of Animal Science,⁴ College of Agriculture and Life Sciences, Texas A&M University, College Station, Texas 77843 Department of Veterinary Anatomy, Histology, and Embryology,⁵ Justus-Liebig-University, 35392 Giessen, Germany

Osteopontin (OPN) is a component of the extracellular matrix that interacts with cell surface receptors, including integrins, to mediate cell adhesion, migration, differentiation, survival, and immune function. In pregnant mice and primates, OPN has been detected in decidualized stroma and is considered to be a gene marker for decidualization. Decidualization involves transformation of spindle-like fibroblasts into polygonal epithelial-like cells that are hypothesized to limit conceptus trophoblast invasion through the uterine wall during invasive implantation. Decidualization is not considered characteristic of species with noninvasive implantation, such as domestic animals. However, the extent of trophoblast invasion between sheep and pigs differs, with sheep exhibiting erosion of the uterine luminal epithelium (LE) and fusion of trophectoderm with LE to form syncytia, and pigs maintaining an intact LE throughout pregnancy. Therefore, the present study measured changes in the decidualization marker genes OPN, desmin, and alpha smooth muscle actin (SMA) in ovine and porcine uterine stroma throughout pregnancy. The morphology of endometrial stromal cells in pregnant ewes changes following conceptus attachment, with cells increasing in size and becoming polyhedral in shape by Day 35 of pregnancy. Expression of OPN mRNA and protein, as well as desmin and SMA proteins, was observed in this same uterine stromal compartment. In contrast, no morphological changes in uterine stroma nor induction of OPN mRNA and protein, or desmin protein, were detected during porcine pregnancy. Interestingly, SMA protein was absent on Day 20, but prominent in uterine stroma of pregnant pigs on Day 45. Collectively, these results indicate that the uterine stroma of sheep undergoes a program of differentiation similar to decidualization in invasive implanting species, whereas porcine stroma exhibits differentiation that is more limited than that in sheep, rodents, or primates. Results suggest that uterine stromal decidualization is common to species with different types of placentation, but the extent is variable and correlates with the depth of trophoblast invasion during implantation.

¹ Correspondence: Greg A. Johnson, Department of Veterinary Anatomy and Public Health, College of Veterinary Medicine, Texas A&M University, College Station, TX 77843-4458. FAX: 979 847 8981; gjohnson{at}cvm.tamu.edu