The placenta develops from the chorion frondosum( foetal origin) and decidua basalis ( maternal origin).
Smooth, glistening and is covered by the amnion which is reflected on the cord.
The umbilical cord is inserted near or at the center of this surface and its radiating branches can be seen beneath the amnion.
Dull greyish red in colour and is divided into 15-20 cotyledons.
Each cotyledon is formed of the branches of one main villus stem covered by decidua basalis.
Functions Of The Placenta
Production of enzymes
Production of pregnancy associated plasma proteins (PAPP)
Hormones Secreted by the Placenta
Human chorionic gonadotrophin(hCG)
It is a glycoprotein produced by the syncytiotrophoblast.
- It supports the corpus luteum in the first 10 weeks of pregnancy to produce oestrogen and progesterone until the syncytiotrophoblast can produce progesterone.
HCG rises sharply after implantation, reaches a peak of 100.000 mIU/ml about the 60 th day of pregnancy
then falls sharply by the day 100 to 30.000 mIU/ml and is maintained at this level until term.
Human placental lactogen (hPL)
It is a polypeptide hormone produced by the syncytiotrophoblast.
- The supposed actions of hPL include:
increasing free fatty acids which provide a source of energy for mother and foetal nutrition.
b. Inhibition of gluconeogenesis:
thus spare both glucose and protein explaining the anti-insulin effect of hPL.