placenta
Sign in to saveThe placenta (: 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 physiology during pregnancy. The placenta connects to the fetus via the umbilical cord, and on the opposite aspect to the maternal uterus in a species-dependent manner. In humans, a thin layer of maternal deci
AI overview
The placenta is a temporary organ that develops during pregnancy to connect a developing fetus to the uterus and facilitate the exchange of nutrients, oxygen, and waste between mother and baby. It also produces hormones that regulate the physical changes needed to support pregnancy in both mother and fetus.
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Key facts
- Embryology.Name
- Placenta
- Embryology.Latin
- placenta
- Embryology.Image
- Healthy Placenta.jpg
- Embryology.Caption
- Human placenta from just after birth with the umbilical cord in place
- Embryology.Image2
- Placenta.svg
- Embryology.Caption2
- Human placenta shown in uterus connected to fetus with umbilical cord
- Embryology.Precursor
- Decidua basalis, chorion frondosum
via Wikipedia infobox
Article
24 sectionsContents
- Evolution and phylogenetic diversity
- Structure
- Gene and protein expression
- Physiology
- Development
- Placental circulation
- Maternal placental circulation
- Fetoplacental circulation
- Birth
- Microbiome
- Physiology of placenta
- Nutrition and gas exchange
- Excretion
- Immunity
- Hormonal regulation
- Immunological barrier
- DNA methylation
- Other
- Clinical significance
- Society and culture
- Additional images
- See also
- References
- External links
The placenta (: 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 physiology during pregnancy. The placenta connects to the fetus via the umbilical cord, and on the opposite aspect to the maternal uterus in a species-dependent manner. In humans, a thin layer of maternal decidual (endometrial) tissue comes away with the placenta when it is expelled from the uterus following birth (sometimes incorrectly referred to as the 'maternal part' of the placenta). Placentas are a defining characteristic of placental mammals, but are also found in marsupials and some non-mammals with varying levels of development.
Mammalian placentas probably first evolved about 150 million to 166 million years ago. The protein syncytin, found in the outer barrier of the placenta (the syncytiotrophoblast) between mother and fetus, has a certain RNA signature in its genome that has led to the hypothesis that it originated from an ancient retrovirus: essentially a virus that helped pave the transition from egg-laying to live-birth.