trofoblasti

Trofoblasti are the cells that form the outer layer of the mammalian blastocyst and participate in implantation and placental development. They are derived from the trophectoderm, the first lineage to differentiate from the inner cell mass after fertilization.

During placentation, trofoblasti differentiate into two main lineages: cytotrofoblasts, which proliferate to form a continuous monolayer, and syncytiotrophoblasts, which arise by fusion of cytotrofoblasts and establish the direct interface with maternal blood. A third population, extravillous trofoblasts, invades the maternal decidua and remodels the spiral arteries to increase uteroplacental blood flow, supporting fetal growth.

Functions of trofoblasti include mediating nutrient and gas exchange between mother and fetus, producing hormones such as human chorionic gonadotropin (hCG), progesterone, and estrogens, and contributing to immune regulation at the maternal–fetal interface. The syncytiotrophoblast layer also forms a barrier that protects the fetus from maternal blood components while allowing exchange.

Clinical relevance is significant: impaired trofoblast invasion or function is associated with obstetric complications such as preeclampsia, intrauterine growth restriction, and placenta accreta. Trophoblastic diseases, including hydatidiform mole and choriocarcinoma, arise from trophoblastic tissue. Because trofoblasti play a central role in implantation and placental development, their biology is a central focus in reproductive medicine and developmental biology.