The foetal blood is separated from the syncytiotrophoblast with all EXCEPT:
(Decidua-parietalis) (25, 36-Duta 6th)Decidua-vera or parietalis - the rest of the deciduas lining the uterine cavity outside the site of implantation.* Foetal blood now circulate through the villi, while maternal blood circulate through intervillous space (69-IBS- Embryology 7th)* Synocytiotrophoblast grows into the endometrium. As endometrium is eroded, some of its blood vessels are opened up, and blood from them fills the lacunar spaces {intervillous space)* Each trabeculus is initially made up entirely by syncytiotrophoblast. Now the cells of the cytotrophoblast begin to multiply and grow into each trabeculus. The trabeculus thus comes to have a central core of cytotrophoblast covered by an outer layer of syncytium. It is surrounded by maternal blood filling the lacunar space. The trabeculus is now called is primary villous.
Foetal blood capillary membrane
Mesenchyme inter villous blood space
Cytotrophoblast
Decidua - parietalis
Miscellaneous (Gynae)