The
human placenta is a confounding organ. Made up almost entirely of
tissue from the fetus, not the mother, the placenta should be attacked
as a foreign invader by the mother’s immune system. And yet, the
placenta makes a nine month pregnancy possible. How?
First, a description of the human placenta:
About four to five days after fertilization, the embryo is a hollow ball of about 100 cells (blastocyst).
Inside and attached to the hollow ball is a group of cells that will
eventually become the fetus, while the outer ball of cells (trophoblast)
will attach to the lining of the uterus and become the placenta. The
attachment is as close as any two human beings will ever be. Once
attached, the trophoblast will actually reroute the mother’s blood
supply to feed the fetus, via the umbilical cord. By the time the baby
is born, the “interface” between mother and placenta is about 12 square
meters.
So how does the placenta keep the mother’s immune
system at bay? Researchers found that the placenta releases exosomes:
small packages packed with information telling the mother’s immune
system to back off. Ian Sargent, a reproductive immunologist at the
University of Oxford in England, describes human reproduction: “It’s
hijacked the immune system and used it for its own purposes.”
After birth, the placenta is expelled from the mother’s body and the
umbilical cord is cut, thus ending the physical connection between
mother and child. Controversy over what to do with the placenta after
birth (some people think it’s a good idea to eat it) has recently
resurfaced in the media. Regardless of what happens to it after those
nine months, the placenta is an amazing organ.
Picture courtesy of:
http://www.sciencephoto.com/
Sources:
http://www.sciencenews.org/
The
human placenta is a confounding organ. Made up almost entirely of
tissue from the fetus, not the mother, the placenta should be attacked
as a foreign invader by the mother’s immune system. And yet, the
placenta makes a nine month pregnancy possible. How?
First, a description of the human placenta:
About four to five days after fertilization, the embryo is a hollow ball of about 100 cells (blastocyst). Inside and attached to the hollow ball is a group of cells that will eventually become the fetus, while the outer ball of cells (trophoblast) will attach to the lining of the uterus and become the placenta. The attachment is as close as any two human beings will ever be. Once attached, the trophoblast will actually reroute the mother’s blood supply to feed the fetus, via the umbilical cord. By the time the baby is born, the “interface” between mother and placenta is about 12 square meters.
So how does the placenta keep the mother’s immune system at bay? Researchers found that the placenta releases exosomes: small packages packed with information telling the mother’s immune system to back off. Ian Sargent, a reproductive immunologist at the University of Oxford in England, describes human reproduction: “It’s hijacked the immune system and used it for its own purposes.”
After birth, the placenta is expelled from the mother’s body and the umbilical cord is cut, thus ending the physical connection between mother and child. Controversy over what to do with the placenta after birth (some people think it’s a good idea to eat it) has recently resurfaced in the media. Regardless of what happens to it after those nine months, the placenta is an amazing organ.
Picture courtesy of:
http://www.sciencephoto.com/
Sources:
http://www.sciencenews.org/
First, a description of the human placenta:
About four to five days after fertilization, the embryo is a hollow ball of about 100 cells (blastocyst). Inside and attached to the hollow ball is a group of cells that will eventually become the fetus, while the outer ball of cells (trophoblast) will attach to the lining of the uterus and become the placenta. The attachment is as close as any two human beings will ever be. Once attached, the trophoblast will actually reroute the mother’s blood supply to feed the fetus, via the umbilical cord. By the time the baby is born, the “interface” between mother and placenta is about 12 square meters.
So how does the placenta keep the mother’s immune system at bay? Researchers found that the placenta releases exosomes: small packages packed with information telling the mother’s immune system to back off. Ian Sargent, a reproductive immunologist at the University of Oxford in England, describes human reproduction: “It’s hijacked the immune system and used it for its own purposes.”
After birth, the placenta is expelled from the mother’s body and the umbilical cord is cut, thus ending the physical connection between mother and child. Controversy over what to do with the placenta after birth (some people think it’s a good idea to eat it) has recently resurfaced in the media. Regardless of what happens to it after those nine months, the placenta is an amazing organ.
Picture courtesy of:
http://www.sciencephoto.com/
Sources:
http://www.sciencenews.org/
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