Intermediate trophoblast

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

Function
The function of the implantation site intermediate trophoblast is to anchor the placenta to the maternal tissue.

Histomorphology

 * Villous intermediate trophoblast
 * polyhedral and uniform nuclei
 * prominent cell border; abundant eosinophilic to clear cytoplasm
 * cohesive growth
 * Implantation site intermediate trophoblast
 * pleomorphic irregular nuclei, large and hyperchromatic, may show multinucleation
 * abundant eosinophilic to amphophilic cytoplasm
 * infiltrative growth (splitting muscle, replacing vascular wall ...etc)
 * Chorionic-type intermediate trophoblast
 * round to polyhedral nuclei, may multinucleation
 * abundant eosinophilic to clear cytoplasm
 * cohesive growth

Pathology
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