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Placenta: 1st trimester
All chorionic villi extend into the intervillous space filled with maternal blood. Each villus, with a central core of embryonic connective tissue and embryonic blood vessels, is covered by an inner layer of cytotrophoblastic cells and an outer layer of syncytiotrophoblast. 400x
![Intervillous space <p>All chorionic villi extend into the intervillous space filled with maternal blood. Each villus, with a central core of embryonic connective tissue and embryonic blood vessels, is covered by an inner layer of cytotrophoblastic cells and an outer layer of syncytiotrophoblast. 400x</p>](https://digitalhistology.org/wp-content/uploads/2018/03/O.R.F.P.04.P02.png)
Intervillous space
All chorionic villi extend into the intervillous space filled with maternal blood. Each villus, with a central core of embryonic connective tissue and embryonic blood vessels, is covered by an inner layer of cytotrophoblastic cells and an outer layer of syncytiotrophoblast. 400x
![- Maternal blood <p>All chorionic villi extend into the intervillous space filled with maternal blood. Each villus, with a central core of embryonic connective tissue and embryonic blood vessels, is covered by an inner layer of cytotrophoblastic cells and an outer layer of syncytiotrophoblast. 400x</p>](https://digitalhistology.org/wp-content/uploads/2018/03/O.R.F.P.04.P03.png)
- Maternal blood
All chorionic villi extend into the intervillous space filled with maternal blood. Each villus, with a central core of embryonic connective tissue and embryonic blood vessels, is covered by an inner layer of cytotrophoblastic cells and an outer layer of syncytiotrophoblast. 400x
![Floating villi <p>All chorionic villi extend into the intervillous space filled with maternal blood. Each villus, with a central core of embryonic connective tissue and embryonic blood vessels, is covered by an inner layer of cytotrophoblastic cells and an outer layer of syncytiotrophoblast. 400x</p>](https://digitalhistology.org/wp-content/uploads/2018/03/O.R.F.P.04.P01.png)
Floating villi
All chorionic villi extend into the intervillous space filled with maternal blood. Each villus, with a central core of embryonic connective tissue and embryonic blood vessels, is covered by an inner layer of cytotrophoblastic cells and an outer layer of syncytiotrophoblast. 400x
![- Embryonic connective tissue <p>All chorionic villi extend into the intervillous space filled with maternal blood. Each villus, with a central core of embryonic connective tissue and embryonic blood vessels, is covered by an inner layer of cytotrophoblastic cells and an outer layer of syncytiotrophoblast. 400x</p>](https://digitalhistology.org/wp-content/uploads/2018/03/O.R.F.P.04.P04.png)
- Embryonic connective tissue
All chorionic villi extend into the intervillous space filled with maternal blood. Each villus, with a central core of embryonic connective tissue and embryonic blood vessels, is covered by an inner layer of cytotrophoblastic cells and an outer layer of syncytiotrophoblast. 400x
![- Embryonic blood vessels <p>All chorionic villi extend into the intervillous space filled with maternal blood. Each villus, with a central core of embryonic connective tissue and embryonic blood vessels, is covered by an inner layer of cytotrophoblastic cells and an outer layer of syncytiotrophoblast. 400x</p>](https://digitalhistology.org/wp-content/uploads/2018/03/O.R.F.P.04.P05.png)
- Embryonic blood vessels
All chorionic villi extend into the intervillous space filled with maternal blood. Each villus, with a central core of embryonic connective tissue and embryonic blood vessels, is covered by an inner layer of cytotrophoblastic cells and an outer layer of syncytiotrophoblast. 400x
![- Cytotrophoblast > <p>In the early placenta, cytotrophoblastic cells form a continuous, single-cell layer surrounding the embryonic connective tissue. These cells give rise to the multinucleated syncytiotrophoblast that lines the intervillous space. </p>](https://digitalhistology.org/wp-content/uploads/2018/03/O.R.F.P.04.P06.png)
- Cytotrophoblast >
In the early placenta, cytotrophoblastic cells form a continuous, single-cell layer surrounding the embryonic connective tissue. These cells give rise to the multinucleated syncytiotrophoblast that lines the intervillous space.
![- Syncytiotrophoblast <p>In the early placenta, cytotrophoblastic cells form a continuous, single-cell layer surrounding the embryonic connective tissue. These cells give rise to the multinucleated syncytiotrophoblast that lines the intervillous space. </p>](https://digitalhistology.org/wp-content/uploads/2018/03/O.R.F.P.04.P07.png)
- Syncytiotrophoblast
In the early placenta, cytotrophoblastic cells form a continuous, single-cell layer surrounding the embryonic connective tissue. These cells give rise to the multinucleated syncytiotrophoblast that lines the intervillous space.