Primary chorionic will develop between13th and 15th day after the ovulation (during 4th week of gestation) and mark the beginning of the placental development. At the same time, the formation of blood vessels starts in the extraembryonic mesoderm of the yolk sac, the connecting stalk and the chorion. By 18 to 21 days (during the 5th week of gestation), the villi have become branched and the mesenchymal cells within the villi have differentiated into blood capillaries and formed an arteriocapillary venous network. Chorionic villi cover the intire surface of gestational sac until the end of the 8th week. At the time, the villi on the side of the chorion proliferate towards the decidua basalis to form the chorion frondosum, which develops into the definitive placenta. The villi in contact with the decidua capsularis begin to degenerate and form an vascular shell, known as the chorion leave or smooth chorion. The placenta is mostly derived from fetal tissues, when maternal component contributes little to the architecture of definitive placenta.
Normal placentation requires a progressive transformation of the spiral arteries and an infiltration of trophoblastic cells into the placental bed. These physiological changes normally extend into the inner third of the myometrium, and in normal pregnancies, all the spiral arteries are transformed into uteroplacental arteries before 20 weeks of gestation. In some cases of early pregnancy failure and pregnancy-induced hypertention, there is an adequate placentation with a defective transformation of spiral arteries.
3D Power Doppler Studies in Assessment of Early Chorionic Circulation
New developments of the cutting edge of the ultrasound technology enabled us to expand investigations of early placental vascular supply. 3D power Doppler is able to depict the integral 3D image of placenta and embryo and their vascular network. Additionally, it is possible to quantify and express numerically data related to vascular signals in the investigated volume.
Normal placentation requires a progressive transformation of the spiral arteries and an infiltration of trophoblastic cells into the placental bed. These physiological changes normally extend into the inner third of the myometrium, and in normal pregnancies, all the spiral arteries are transformed into uteroplacental arteries before 20 weeks of gestation. In some cases of early pregnancy failure and pregnancy-induced hypertention, there is an adequate placentation with a defective transformation of spiral arteries.
3D Power Doppler Studies in Assessment of Early Chorionic Circulation
New developments of the cutting edge of the ultrasound technology enabled us to expand investigations of early placental vascular supply. 3D power Doppler is able to depict the integral 3D image of placenta and embryo and their vascular network. Additionally, it is possible to quantify and express numerically data related to vascular signals in the investigated volume.
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