THE DISTRIBUTION OF LAMININS AND FIBRONECTINS IS MODULATED DURING EXTRAVILLOUS TROPHOBLASTIC CELL-DIFFERENTIATION AND DECIDUAL CELL RESPONSE TO INVASION IN THE HUMAN PLACENTA

We studied the distribution of laminin (Ln) alpha 1-alpha 3, beta 1-be ta 3, and gamma 1 chains, and of the extradomain-A (EDA) and EDB and t he oncofetal epitope of fibronectin (Onc-Fn) in extravillous trophobla stic cells and decidua in the human placenta by immunohistochemistry. We found that the transition from villous to extravillous trophoblast was accompanied by emergence of immunoreactivity for EDA-, EDB-, and O nc-Fn among the cells. Further more, whereas the villous trophoblastic basement membrane (BM) contains Ln alpha 1, alpha 2, beta 1, beta 2, and gamma 1 chains, immunoreactivity for Ln alpha 1, beta 1, and gamma 1, but not for Ln alpha 2 and beta 2 chains, was detected in associat ion with extravillous trophoblastic cells. Interestingly, although imm unoreactivity for the Ln alpha 1, alpha 2, beta 1, beta 2, and gamma 1 chains was detected in all decidual cell BMs, EDB-Fn and Onc-Fn were detected only in decidua that had been invaded by the trophoblast. In summary, our results describe distinct changes in the distribution of Ln and Fn isoforms during the differentiation of villous trophoblast i nto extravillous trophoblastic cells. Furthermore, EDB- and Onc-Fn are preferentially found in decidua that has been invaded by the trophobl ast, indicating that the deposition of these Fn isoforms reflects a de cidual cell response to invasion.