Expression of Cx43 and Pax3 proteins in the human placental villi and decidua during early pregnancy

To study the expression and roles of Connexin43 (Cx43) and Paired-box3 (Pax3) proteins in the human Chorionic villi and decidua during early pregnancy, Cx43 and Pax3 protein expression in the human placental villi and decidua at 5-7 weeks of early pregnancy was studied by immunohistochemistry (SABC). Integrated optical density (IOD) of Cx43 and Pax3 protein expression was obtained by using special image analysis software. Cx43 and Pax3 proteins were expressed in all trophoblastic cells, cells of villi central axis and decidual cells. IOD of Cx43 and Pax3 proteins expressed in the syncytiotrophoblast decreased from 5 to 7 weeks, while Cx43 and Pax3 expressed in cytotrophoblast cells and decidual cells showed increased IOD during the same period. The differences between any two groups were statistically significant (P<0.05). Cx43 and Pax3 proteins were expressed during differentiation and development of placental villous cells in early phases of pregnancy. We propose that Cx43 and Pax3 may participate in endometrial decidualization and the regulation of trophoblastic invasion and differentiation. It is likely that Cx43 and Pax3 play critical roles in cell proliferation and differentiation during the processes of chorionic villi initiation/development and placental morphogenesis.