IFPA Award in Placentology Lecture – Characteristics and Significance of Trophoblast Giant Cells

Schematic diagram of an early mouse post-implantation conceptus (∼E7.5) and a post-midgestation placenta (∼E12.5 onwards), summarizing the localization of trophoblast giant cell subtypes. Parietal or primary giant cells (depicted in dark pink) line the early implantation site. Secondary giant cells can be subdivided into several groups. Giant cells that differentiate at the margins of the ectoplacental cone (depicted in lighter pink and yellow), especially those at its tip, are invasive and make contact with maternal spiral arteries. In the later placenta, giant cells are located at the border towards the maternal decidua. Giant cells are also associated with maternal blood canals (canal giant cells) and with sinusoids that carry maternal blood in the placental labyrinth layer (sinusoidal giant cells). Some of the most prominent functions of specific giant cell subtypes and the overall functions of giant cells are listed. E=embryo.

Examples of trophoblast giant cells with nuclear invaginations or fragmentations that differentiated from trophoblast stem cells in vitro. Arrows point towards indentations of the nucleus or nuclear fragments surrounded by nuclear membrane. Note also the doughnut shape of some trophoblast giant cell nuclei in (A). (A), (B), and (D): fluorescent nuclear staining was performed with 4,6-diamidino-2-phenylindole (DAPI). The cellular outline is indicated by the red dotted line. The inset in (B) shows an overexposed image of the same cell visualizing the cytoplasmic perimeter. (C) Differential interference contrast (DIC) image and (D) DIC/DAPI fluorescence overlay of the same area. Magnification bar: 100μm.