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, 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 multinucleation
- * abundant eosinophilic to amphophilic cytoplasm
- * infiltrative growth
- 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 : implantation site IT
- Placental site nodule : chorionic-type IT
- Placental site trophoblastic tumour : implantation site IT
- Epithelioid trophoblastic tumour : chorionic-type IT
