How Does the Placenta Look Like?

The human placenta is a maternal organ which has an important role in supplying oxygen as well as nutrients to the fetus through umbilical cord during pregnancy. It composes of fetal and maternal components (known as Decidua basalis). As shown in the below figure, fetal vessels spread over the placental surface of the fetal side. Therefore, the fetal side is almost occupied by significant fetal arterial and venous blood flows.

The fetal side of the placenta (taken from the department of pathology)
The maternal side of the placenta (taken from the department of pathology)
Those fetal vessels branch out and finally form a complex structure of villous trees which are grouped in the unit known as 'cotyledons' which look discriminated by valleys in the maternal side. The maternal bloods are supplied in the intervillous space through spiral arteries in decidua of the maternal side which is attached to the uterine wall. Oxygen and other gases are transported through fetal chorionic villi which broadly contact with maternal blood. Our dissection study of the placenta shows that the structural complexity of villous trees, as depicted in the below figure, makes it hard to anatomically distinguish between fetal and maternal compartments of the placenta through visual inspection. In spite of the difficulty, recent studies show the feasibility of figuring out placental structure and functions using non-invasive magnetic resonance imaging (MRI) techniques.

Further readings
  1. Dekan, S. & Linduska, N., 2011. Normal and Pathological Placental Development: MRI and Pathology. In D. Prayer, ed. Fetal MRI. Berlin, Heidelberg: Springer Berlin Heidelberg, pp. 403–442.
  2. Benirschke, K., Burton, G.J. & Baergen, R.N., 2012. Pathology of the Human Placenta, Springer Berlin Heidelberg.
  3. You. W, 2016. Novel technology for functional MRI of the moving fetus, Brain in God.
  4. You. W, 2016. A Talk on Fetal fMRI at SPIE Medical Imaging, Brain in God.

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