Tissue processing and embedding and staining: four sections of each placenta about 2x2cm were taken at 3,6,9 and 12 O'clock position from chorionic plate
to basal plate and from central to periphery.
The two umbilical arteries transport the fetal blood to the placenta, and then they branch off in the chorionic plate
, thus creating networks of capillaries in the chorionic villi.
(2) Thrombosis of fetal chorionic plate
vessels, especially in the presence of severe fetal inflammatory response or funisitis, is observed (Figure 15).
In the stem villi and in the chorionic plate
there was moderate hardening of the stroma.
High-grade FVM is manifest by the finding of more than one focus of avascular villi (a cumulative assessment of >45 avascular villi over 3 sections examined or an average of >15 villi per section) with or without thrombus, or 2 or more occlusive or nonocclusive thrombi in chorionic plate
or major stem villi, or multiple nonocclusive thrombi.
The chorionic plate
area specifies the placental surface area covering the uterus and defines, how many maternal spiral arteries and veins are potential suppliers to surface area (7).
Placental cysts are hypoechoic and can be located within the placental tissue or under the chorionic plate
with proposed origin from the trophoblastic X cell.
Grade II: The placental tissue contains randomly dispersed echoes and is divided by comma like reflective structures continuous with the chorionic plate
. The marked indentations of the chorionic plate
do not reach the basal plate, which is well defined by small linear highly reflective areas.
The multiple fragments of villous parenchyma, some with overlying chorionic plate
, were examined for lesions.
The chorionic plate
was not identified and there were thick ropy stem villi that have been shorn off the villous parenchyma (Figure 4).
As the pregnancy advanced, the cystic spaces moved toward the chorionic plate
. The chorionic plate
vessels, including both the arteries and veins, became progressively dilated and aneurysmal.
Immediately just before or after entering the chorionic plate
the two umbilical arteries are joined by transverse connection.
A wide-based cylinder is formed, bounded on one side by fetal retroperitoneal space, and chorionic plate
of placenta at the other end.
Likewise, meconium staining of the chorioamnionic membrane and chorionic plate
may be an indicator of fetal jeopardy, possibly associated with tissue hypoxia.
These vascular anastomoses occur at the level of the umbilical cord or chorionic plate
. The acardia has no placenta-parenchymal vascular connections and is therefore more akin to a conjoined twin than a twin-twin transfusion.