[Utero-trophoblastic interface: transitory stage in human placentation].

: In the past, the intervillous space of the human placenta has been studied on samples provided by spontaneous abortions. Using the endocavitary ultrasonography and the chorionoscopy in normal pregnancies, the intervillous space during the first trimester has been observed as filled by a plasmatic fraction cell free of the maternal blood. During the first trimester, the human placenta doesn't have its theoretical functional specificities.