<prompt> Thickness of placental barrier in early pregnancy0.5 mm0.05 mm0.025 mm0.25 mm  <response>: Placental barrier in early pregnancy consists of Synctiotrophoblast Cytotrophoblast Basement membrane Stromal tissue Endothelium of fetal capillary wall It is about 0.025 mm thick Ref: Dutta Obs 9e pg 30. 