[2] Syncytialization of cytotrophoblastic cells can be induced in vitro through multiple signalling molecules including epidermal growth factor, glucocorticoids, and human chorionic gonadotropin.

[3][4][5] The invasive lineage creates cytotrophoblasts that are essential in the process of implantation and forming a fully functional placenta.

Multinucleated giant cells (small syncytia) are found in the placental bed and myometrium as a result of the fusion of interstitial cytotrophoblasts.

The primary function of the endovascular cytotrophoblast is to penetrate maternal spiral arteries and route the blood flow through the placenta for the growing embryo to use.

The cytotrophoblast secretes proteolytic enzymes to break down the extracellular matrix between the endometrial cells to allow finger-like projections of trophoblast to penetrate through.

Projections of cytotrophoblast and syncytiotrophoblast pull the embryo into the endometrium until it is fully covered by endometrial epithelium, save for the coagulation plug.

Clinical symptoms of pre-eclampsia in the mother are most commonly high blood pressure, proteinuria and edema.