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Reproduction and growth
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Describe the formation and functions of placenta?
2 Answers
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Nur `isyah Suffyea Binti Sabri
Sekolah Menengah Kebangsaan Jalan Empat
answered Wednesday, 23rd August 2017
Reportplacenta is formed around the 28th day of menstruation where the endometrium does not shrink in size because fertilization occurs so progesterone is released at constant rate.
placenta acts as the barrier between the mother's blood circulation and womb's blood circulation because they have different pressure; pressure in mother's blood circulation is higher whilst pressure in the womb's b.c is lower.
It also filters harmful substance from getting into the womb's blood circulation such as drugs, carcinogen, viruses etc.
It acts as a medium for gas changing, oxygen and carbon dioxide.
It releases estrogen and progesterone (temporary)
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The placenta begins to develop upon implantation of the blastocyst into the maternal endometrium. The outer layer of the blastocyst becomes the trophoblast, which forms the outer layer of the placenta. This outer layer is divided into two further layers: the underlying cytotrophoblast layer and the overlying syncytiotrophoblast layer. The syncytiotrophoblast is a multinucleated continuous cell layer that covers the surface of the placenta. It forms as a result of differentiation and fusion of the underlying cytotrophoblast cells, a process that continues throughout placental development. The syncytiotrophoblast (otherwise known as syncytium), thereby contributes to the barrier function of the placenta.
The placenta grows throughout pregnancy. Development of the maternal blood supply to the placenta is complete by the end of the first trimester of pregnancy (approximately 12–13 weeks).