Intermediate trophoblast is a distinct subtype of trophoblastic tissue that arises from the cytotrophoblast.
It is sub-categorized by location:
Villous intermediate trophoblast:
at anchoring villi of trophoblastic column
Implantation site intermediate trophoblast:
at implantation site (or basal plate), differentiated from villous intermediate trophoblast
Chorionic-type intermediate trophoblast
at chorionic laeve of fetal membrane, differentiated from villous intermediate trophoblast
The function of the implantation site intermediate trophoblast is to anchor the placenta to the maternal tissue.
Villous intermediate trophoblastpolyhedral and uniform nuclei
prominent cell border; abundant eosinophilic to clear cytoplasm
cohesive growth
Implantation site intermediate trophoblastpleomorphic irregular nuclei, large and hyperchromatic, may multinucleation
abundant eosinophilic to amphophilic cytoplasm
infiltrative growth (splitting muscle, replacing vascular wall ...etc)
Chorionic-type intermediate trophoblastround to polyhedral nuclei, may multinucleation
abundant eosinophilic to clear cytoplasm
cohesive growth
Intermediate trophoblasts are thought to be the cell of origin for:
Exaggerated placental site (EPS): implantation site IT
Placental site nodule (PSN): chorionic-type IT
Placental site trophoblastic tumour (PSTT): implantation site IT
Epithelioid trophoblastic tumour (ETT): chorionic-type IT
