Normal·Reproductive·Placenta
Placenta — chorionic villi with syncytiotrophoblast
Stain: H&E·Magnification: 20x·Tissue: Chorionic villus·4 labeled regions
Wikimedia Commons · File:Chorionic_villi_-_intermed_mag.jpg · https://commons.wikimedia.org/wiki/File:Chorionic_villi_-_intermed_mag.jpg (CC-licensed)
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Fetal villi bathed in maternal blood within intervillous space. Two trophoblast layers (cytotrophoblast inner, syncytiotrophoblast outer) thin as pregnancy advances to facilitate gas/nutrient exchange. Syncytiotrophoblast secretes hCG, hPL, estrogen, progesterone.
Labeled regions (4)
- 1Syncytiotrophoblast
Outer multinucleated layer covering villus surface. Secretes β-hCG (basis of pregnancy test) + hPL + steroids.
- 2Cytotrophoblast (Langhans)
Inner mononuclear stem-cell layer beneath syncytium. Thins / fragments by third trimester. Source of choriocarcinoma.
- 3Fetal capillary
Within villus core — carries fetal blood (Hb F). Maternal-fetal exchange occurs across the trophoblast layers.
- 4Intervillous space
Bathed in maternal blood from spiral arteries. Drug + IgG transfer + gas/nutrient exchange occurs here.
