Figure 7

The subplacenta. (A) Initial pregnancy, HE. Originating from the subplacenta (sp), extraplacenta or extravillous trophoplast (evt) and syncytial streamers (sys) continue to the decidua. (B) Early pregnancy, HE. The subplacenta is supplied by fetal vessels (fv) and maternal blood channels (mbc). (C) Same stage, PAS, counterstained with HE. Each fold inside the subplacenta possesses a band of fetal mesenchyme (fm), including fetal vessels, lined with highly proliferative cytotrophoblast (ct). On the other side, syncytial trophoblast (syt) occurs that has accumulated 1–2 glycol containing substances, e.g. carbohydrates such as glycogen or mucopolysacharides, or glycoproteins or proteoglycans. (D) Same stage, TEM. Subplacental cytotrophoblast is active in proliferation. Scale bars = 0.1 mm for histology and 2 μm for TEM.