Onset of maternal blood flow [1314

At the end of the first trimester the trophoblastic plugs become pervious and maternal blood cells enter the

Trophoblast differentiation and subtypes Trophoblast of blastocyst

Trophoblast differentiation and subtypes Trophoblast of blastocyst

Villous

Trophoblastic cell column syncytiotrophoblast

Villous

Trophoblastic cell column syncytiotrophoblast

Interstitial trophoblast

Intramural trophoblast 1

Endovascular trophoblast

Multinucleated trophoblast giant cells

Fig. 3.4 Trophoblast differentiation and subtypes. The trophoblast lineage is the first to develop at the blastocyst stage. From this stage onwards, further differentiation leads to the generation of the syncytiotrophoblast and subsequently into the two main trophoblast types of placental villi, villous cytotrophoblast and villous syncytiotrophoblast. The trophoblast cells that start to invade maternal tissues are termed extravillous trophoblast with its respective subtypes.

intervillous space establishing the first arterial blood flow to the placenta. The inflow starts in those upper parts of the placenta that are closer to the endometrial epithelium (Fig. 3.3). These sites are characterized by a slight delay in development since the deeper parts have been the first to develop directly after implantation (Fig. 3.3). Therefore, at these upper sites the plugs inside the vessels contain fewer cells, enabling blood cells to penetrate the plugs earlier, and blood flow starts first at these sites. Here the placental villi degenerate in larger parts and the chorion becomes secondarily smooth. The regression leads to the formation of the fetal membrane or chorion laeve. The remaining part of the placenta develops into the chorion frondosum, the definitive disc-shaped placenta.

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Pregnancy Diet Plan

Pregnancy Diet Plan

The first trimester is very important for the mother and the baby. For most women it is common to find out about their pregnancy after they have missed their menstrual cycle. Since, not all women note their menstrual cycle and dates of intercourse, it may cause slight confusion about the exact date of conception. That is why most women find out that they are pregnant only after one month of pregnancy.

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