[Studies on the immunohistochemical localization of adhesive factors at the site of implantation in the early pregnancy].

We studied the localization of adhesive proteins at the site of implantation in mouse pregnancy (5 days' gestation), and human pregnancy (5-8 weeks' gestation) and in human endometrial culture cells. Immunohistochemical staining of adhesive protein such as fibronectin (FN), laminin, type IV collagen (CIV), subunit A of factor XIII (XIIIA), and subunit S of factor XIII (XIIIs) were performed by indirect enzyme immunoassay to investigate their localization. (1) In mouse pregnancy: FN and XIIIs were stained in trophoblastic giant cells, and CIV was stained in the endometrial epithelium. (2) In human pregnancy: (fetal side) CIV was stained diffusely on the surface of syncytiotrophoblast. FN, CIV, and XIIIA were stained in the stroma of the villi. (maternal side) FN, CIV, and XIIIA were stained in the endometrial stroma. (3) In endometrial culture cells: FN and XIIIA were stained strongly in the stromal cells. These findings demonstrated that FN and XIIIA are produced in the endometrial stromal cells, and suggest that FN, CIV, and XIIIA are concerned with the attachment of the embryo to the uterus. Therefore, these adhesive proteins are important factors in maintaining pregnancy.