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The placenta (pl.: placentas or placentae) is a temporary embryonic and later fetal organ that begins developing from the blastocyst shortly after implantation.It plays critical roles in facilitating nutrient, gas and waste exchange between the physically separate maternal and fetal circulations, and is an important endocrine organ, producing hormones that regulate both maternal and fetal ...
Placenta can also be divided according to what kind of structure it develops from. There are two vessel-rich features in the amniote, the yolk sac and the allantois. When the chorion fuses with the former, the result is a choriovitelline placenta. When it fuses with the latter, the result is a chorioallantoic placenta.
The bleeding may be due to placental abruption, uterine rupture, placenta accrete, undiagnosed placenta previa, or vasa previa. [3] Cesarean section is indicated. Post-partum hemorrhage is defined by the loss of at least 1,000 mL of blood accompanied with symptoms of hypovolemia within 24 hours after delivery.
One hypothesis is that the mass begins as a normal fetus but becomes enveloped inside its twin. [2] The other hypothesis is that the mass is a highly developed teratoma . Fetus in fetu is estimated to occur in 1 in 500,000 live births.
There is only one umbilical vein in the human umbilical cord. [46] In some animals, the mother will gnaw through the cord, thus separating the placenta from the offspring. The cord along with the placenta is often eaten by the mother, to provide nourishment and to dispose of tissues that would otherwise attract scavengers or predators.
The placenta later develops to nourish the embryo, which grows through embryonic and fetal development until childbirth. During this process, the uterus grows to accommodate the growing fetus. [23] When normal labor begins, the uterus forcefully contracts as the cervix dilates, which results in delivery of the infant. [23]
The form of the human placenta is generally classified as a discoid placenta. Within this, the cotyledons are the approximately 15-25 separations of the decidua basalis of the placenta, separated by placental septa. [3] Each cotyledon consists of a main stem of a chorionic villus as well as its branches and sub-branches. [3]
Velamentous Placenta: Normal umbilical cord insertion and velamentous umbilical cord insertion in pregnancy, with and without vasa previa. Specialty: Obstetrics Symptoms: Blood vessel compression, [1] [2] decrease in blood supply to the fetus, [2] [3] impaired growth and development of the fetus. [4] [5] Risk factors