The mechanisms which regulate trophoblast differentiation, proliferation, migration and invasiveness, and the …

• Abstract
• Introduction
• Decidualization
• Blastocyst implantation
• Trophoblast differentiation and function
• Factors involved in the control of CT differentiation
• Extravillous trophoblast function
• The influence of the oxidative balance on trophoblast functions and embryo development
• Pathologic pregnancy
• Therapeutic approaches
• Concluding remarks
• References
• Table 1
• Figures

The formation of floating and anchoring villi begins immediately after nidation. Three stages are recognized in the development of the villi, namely primary, secondary and tertiary villi, the last being characterized by a de-novo formation of capillaries from mesenchymal precursors and thus devoted to feto-maternal exchanges. Villous tree expansion occurs throughtout pregnancy [24].

The specialized villous cell types, i.e. ST and extravillous trophoblast (EVT) cells, originate from cytotrophoblast (CT) stem cells. During blastocyst implantation, CT cells fuse to form an external layer of non-proliferative multinucleated ST which then grows thanks to the steady incorporation of new CT cells. ST exerts a crucial role in feto-maternal exchanges and possesses endocrine activity, releasing hormones involved in the homeostasis of pregnancy such as chorionic gonadotrophin (CG) and placental lactogen (PL). Around day 14 after implantation, CT cells break through the ST layer giving rise to EVT cells, which begin to invade the uterine stroma as trophoblastic cell columns. From the tips of the columns, a subpopulation of these motile and invasive cells moves laterally, to form the trophoblastic shell, and longitudinally to invade deeply the decidua and the deeper portion of the myometrium, where these cells evoke profound changes within the uterine vessels [25].