CHANGES IN THE DISTRIBUTION PATTERN OF GALECTIN-1 AND GALECTIN-3 IN HUMAN PLACENTA CORRELATES WITH THE DIFFERENTIATION PATHWAYS OF TROPHOBLASTS

Human placentation is a complex biological phenomenon that results fro m precisely regulated interactions between cells and the extracellular matrix. Galectin-1 and galectin-3 belong to a newly defined family of galactose-binding lectins that can bind several glycoconjugates such as the basement membrane glycoprotein laminin, and are involved in man y biological events including cell adhesion. In this study, the expres sion of these two galectins in first and third trimester normal human placenta was examined using single and double immunohistochemical stai ning and specific antibodies for galectins and cytokeratins. Galectin- 3 was detected in all trophoblastic lineages including villous cytotro phoblasts and extravillous trophoblasts (trophoblastic cell columns, i nfiltrating trophoblasts, endovascular trophoblasts and placental bed giant cells). On the contrary, galectin-1 distribution was restricted to endometrium. A reduction of galectin-3 expression was observed from the villous trophoblasts to the trophoblastic cell columns. This patt ern correlated with the switch from a proliferative to a migratory phe notype. Galectin-1 and galectin-3 were both detected in maternal decid ual cells. Our data demonstrate a specific pattern of galectin-1 and g alectin-3 expression in trophoblastic tissue, and suggest these lectin s could contribute to cell-cell and cell-matrix interactions of tropho blast during placentation. (C) 1997 W. B. Saunders Company Ltd.