Reference Terms
from Wikipedia, the free encyclopedia
Placenta
The placenta is an ephemeral (temporary) organ present only in female placental vertebrates during gestation (pregnancy). All mammals other than monotremes and (most) marsupials utilise placentas in reproduction, and are known as placental mammals. Also, some species of snakes utilise placentas.
The placenta is composed of two parts, one of which is genetically and biologically part of the fetus, the other part of the mother. It is implanted in the wall of the uterus, where it receives nutrients and oxygen from the mother's blood and passes out waste. This interface forms a barrier, the placental barrier, which filters out some substances which could harm the fetus. However, many other substances are not filtered out, including alcohol and some chemicals associated with smoking cigarettes. Several types of viruses, such as Human Cytomegalovirus, may also cross this barrier; this often leads to various degrees of birth defects in the infant. The placenta is connected to the fetus via the umbilical cord, which is composed of blood vessels and connective tissue. When the fetus is delivered, the placenta is delivered afterwards (and for this reason is often called the afterbirth).
Related Stories
1
2
Health & Medicine News
July 13, 2026
July 13, 2026 Sleeping about an hour and 20 minutes less each night for six weeks caused participants to gain weight and spend more time inactive. Researchers found that even mild, realistic sleep loss, similar to what many adults experience, had measurable ...
July 13, 2026 An unexpected study found that young non-smokers with healthier diets had higher rates of lung cancer, raising questions about whether pesticide exposure from conventionally grown produce could play a role. Researchers stress that the findings are ...
July 13, 2026 Researchers analyzing data from more than 214,000 people found that dementia risk factors differ widely across countries, challenging the idea of a one-size-fits-all prevention strategy. At the same time, they uncovered surprisingly consistent ...
July 13, 2026 Researchers found that bacteria linked to gum disease may help drive the development of calcific aortic valve stenosis by triggering inflammation and calcium buildup in the heart valve. The early findings suggest that keeping gums healthy could play ...
July 12, 2026 Researchers found that tau is essential for turning new experiences into lasting memories by helping organize the brain's memory-storing cells. The mouse study also revealed how abnormal tau may contribute to Alzheimer's by disrupting both the ...
July 12, 2026 A simple, non-invasive ultrasound treatment could one day help injured joints heal instead of remaining trapped in a cycle of damaging inflammation. Researchers at The University of Alabama in Huntsville found that continuous low-intensity ...
July 11, 2026 Scientists have uncovered evidence that serotonin, the chemical best known for regulating mood, may also speed the progression of a common heart valve disease in some people. The research suggests ...
July 11, 2026 Yale scientists discovered two neuron surface proteins that appear to help spread the toxic protein linked to Parkinson’s disease. Blocking these proteins in mice dramatically reduced disease ...
July 11, 2026 Researchers found that the common blood pressure drug telmisartan can significantly improve the performance of the cancer drug olaparib, potentially expanding its benefits beyond patients with BRCA-related tumors. The combination is already being ...
July 11, 2026 An experimental drug called DT-109 reversed severe fatty liver disease in animal studies by repairing the gut and preventing harmful toxins from damaging the liver. The discovery could open the door to a new class of treatments for MASH and ...
July 11, 2026 Researchers found that every pregnancy rewires the brain in its own way, with a second pregnancy bringing a different pattern of changes than the first. The discoveries could lead to better ways to recognize and treat maternal mental health ...
July 10, 2026 Many of the body's biggest flaws are the result of evolution building on old designs instead of starting over. Our spine, eyes, teeth, pelvis, and even certain nerves all reveal compromises that worked well enough for survival but still leave us ...
Latest Headlines
updated 12:56 pm ET
July 10, 2026 A new study found that dietary fiber can determine whether beneficial intestinal worms help reduce inflammation or become essentially inactive. With ...
July 10, 2026 Heavy marijuana smoking may raise the risk of lung cancer and several head and neck cancers, according to growing research, but many important questions remain unanswered. Scientists are still trying ...
July 10, 2026 Scientists have redesigned a key piece of MRI hardware using metamaterials, allowing existing scanners to produce clearer images of difficult-to-see parts of the body in less time. The breakthrough ...
July 10, 2026 A naturally occurring bacterium from amphibian intestines completely eliminated colorectal tumors in mice with a single treatment by both attacking cancer cells and activating the immune system. The ...
July 9, 2026 Scientists found that a modified Mediterranean-style diet with low protein and just enough methionine helped mice live healthier lives while reducing body fat and frailty. Human data also linked ...
July 9, 2026 A new study debunks the long-standing claim that baby rattlesnakes are more dangerous than adults. Researchers found that young rattlesnakes can control their venom just like adults, while adult ...
July 9, 2026 Researchers found that mRNA cancer vaccines can recruit an unexpected immune cell to launch powerful tumor-fighting responses, overturning a long-held assumption about how the vaccines work. The ...
July 9, 2026 A surprising discovery is reshaping scientists' understanding of how humans develop sharp central vision before birth. Instead of blue cone cells migrating away from the retina's center, the study ...
July 9, 2026 Poison control calls involving semaglutide (Ozempic and Wegovy) soared after the drug was approved for weight management, with researchers linking the increase to accidental dosing mistakes rather ...
July 8, 2026 Scientists have created a silicon chip that can write dozens of DNA sequences simultaneously using electricity and water-based enzymes, offering a cleaner alternative to conventional DNA ...