EXPRESSION OF C-FOS IN PORCINE ENDOMETRIUM DURING THE ESTROUS-CYCLE AND EARLY-PREGNANCY

This study determined the pattern of expression of the c-fos onocogene in endometrium from pregnant and cyclic gilts. A transcript of the ex pected 2.2-kb size for the c-fos MRNA was detected in porcine endometr ium from cyclic and pregnant gilts. Expression of endometrial c-fos MR NA was not different for Days 0, 5, 10, 15, or 18 cyclic or pregnant g ilts. However, expression of c-fos mRNA was greater on Day 12 of pregn ancy 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 o f pregnancy. Throughout the estrous cycle and early pregnancy, immunor eactive fos protein was localized to the glandular and surface epithel ial cells as well as myometrial cells. Results of this study indicate that endometrial expression of c-fos mRNA increases on Day 12 of pregn ancy. coinciding with the establishment of maternal recognition of pre gnancy in pigs.