[The 2 differentiation pathways of the human trophoblast].

The trophoblast is the major component of the human placenta. It is directly involved in blastocyst implantation and in feto-placental growth and development. Human trophoblast follows two major pathways of differentiation: the villous trophoblast, bathing in maternal blood of intervillous spaces and involved in matemo-fetal exchanges and in placental endocrine functions; the extra-villous trophoblast involved in uterine spiral arteries remodeling and in the placental anchorage into the uterine wall. It is essential to understand the cellular and molecular mechanisms involved in human trophoblast differentiation: cellular proliferation, migration, invasion and differentiation by cell-cell fusion. Abnormal trophoblast differentiation is implicated in the major pathologies of human pregnancy such as pre-eclampsia and intrauterine growth retardation.