Expression of c-fos in Porcine Endometrium during the Estrous Cycle and Early Pregnancy1

Abstract

This study determined the pattern of expression of the c-fos oncogene in endometrium from pregnant and cyclic gilts. A transcript of the expected 2.2-kb size for the c-fos mRNA was detected in porcine endometrium from cyclic and pregnant gilts. Expression of endometrial c-fos mRNA was not different for Days 0, 5, 10, 15, or 18 cyclic or pregnant gilts. However, expression of c-fos mRNA was greater on Day 12 of pregnancy compared to Day 12 of the estrous cycle. Furthermore, expression of c-fos mRNA was related to developmental stages when pig conceptuses secrete estradiol, the primary determinant for maternal recognition of pregnancy. Throughout the estrous cycle and early pregnancy, immunoreactive fos protein was localized to the glandular and surface epithelial cells as well as myometrial cells. Results of this study indicate that endometrial expression of c-fos mRNA increases on Day 12 of pregnancy, coinciding with the establishment of maternal recognition of pregnancy in pigs.