Reference Terms
from Wikipedia, the free encyclopedia
Embryo
In organisms that reproduce sexually, once a sperm fertilizes an egg cell, the result is a cell called the zygote that has all the DNA of two parents. In plants, animals, and some protists, the zygote will begin to divide by mitosis to produce a multicellular organism.
In animals, the development of the zygote into an embryo proceeds through specific recognizable stages of blastula, gastrula, and organogenesis. The blastula stage typically features a fluid-filled cavity, the blastocoel, surrounded by a sphere or sheet of cells, also called blastomeres.
During gastrulation the cells of the blastula undergo coordinated processes of cell division, invasion, and/or migration to form two (diploblastic) or three (triploblastic) tissue layers. In triploblastic organisms, the three germ layers are called endoderm, ectoderm and mesoderm. However, the position and arrangement of the germ layers are highly species-specific, depending on the type of embryo produced. In vertebrates, a special population of embryonic cells called the neural crest has been proposed as a "fourth germ layer," and is thought to have been an important novelty in the evolution of head structures.
Related Stories
1
2
Health & Medicine News
June 30, 2026
June 30, 2026 A common brain protein may be giving Alzheimer’s disease an unexpected way to spread, carrying toxic Tau proteins from damaged neurons into healthy ones. By blocking these harmful protein packages before they reach new cells, researchers believe ...
June 30, 2026 Creatine is best known as a muscle-building supplement, but scientists are now investigating whether it could also help treat depression by boosting the brain's energy supply. A new review examined five randomized clinical trials involving 238 ...
June 29, 2026 A new stem-cell-inspired technique allows scientists to grow vast numbers of immune-cell progenitors that can be engineered to hunt cancer and strengthen immune responses. In animal studies, the ...
June 29, 2026 Researchers tested experimental PCAI compounds against pancreatic cancer cells and found they had powerful anticancer effects. One leading compound blocked more than 90% of cancer cell migration, ...
June 29, 2026 Fish oil supplements successfully delivered omega-3s to the brain, but a two-year study found no meaningful benefits for memory, cognition, or Alzheimer’s-related brain changes. The results ...
June 29, 2026 Scientists have uncovered a surprising clue that may help explain why multiple sclerosis (MS) progresses rapidly in some people but not others. In brain tissue from patients with severe MS, researchers found large numbers of “foamy” immune cells ...
June 28, 2026 A six-month study of more than 120 adults in their 70s found that high-intensity interval training (HIIT) may offer a key advantage over other forms of exercise: it helped reduce body fat while preserving valuable muscle mass. While moderate and ...
June 28, 2026 Scientists at UCLA have linked long-term exposure to the pesticide chlorpyrifos with a sharply increased risk of Parkinson’s disease. People exposed to the chemical near their homes were more than ...
June 27, 2026 Teens who use cannabis may face a substantially greater risk of developing serious mental health conditions, including psychotic and bipolar disorders, according to a study of more than 463,000 ...
June 27, 2026 Researchers have identified a vitamin B12–based compound that can cross the blood-brain barrier and home in on glioblastoma tumors. In animal studies, the compound accumulated preferentially in tumor tissue and delivered sustained nitric oxide ...
June 27, 2026 Aging may trigger the appearance of specialized stem cells that supercharge the body's ability to create new belly fat. The discovery reveals a potential biological driver of middle-age weight gain and a promising target for future anti-obesity ...
June 26, 2026 The battle between butter and margarine comes down to chemistry. Butter’s naturally occurring fats create rich flavors, golden browning, and flaky baked goods, while margarine’s modified plant oils offer consistency and a longer shelf life. ...
Latest Headlines
updated 12:56 pm ET
June 26, 2026 A new study found that fructose and glucose may look the same on a nutrition label, but the brain treats them very differently. In mice, glucose strongly reduced activity in hunger-promoting brain ...
June 25, 2026 Vitamin B12 is needed in microscopic amounts, but a shortage can have major effects on health and energy. The vitamin was first linked to a lifesaving liver treatment for pernicious anemia nearly 100 ...
June 25, 2026 Researchers found that a rare liver cancer evades immunotherapy by luring immune T cells away from the tumor and trapping them in nearby fibrous tissue. An FDA-approved drug called AMD3100 freed ...
June 25, 2026 Healthy older adults experienced measurable improvements in memory, physical performance, and stress after taking placebo pills for just three weeks. The most surprising finding was that the placebo ...
June 25, 2026 Osteopenia is a common but often overlooked condition that causes bones to become less dense and more fragile. Because it develops silently, many people only discover they have it after a fracture or ...
June 24, 2026 Scientists have discovered a tiny group of neurons in an ancient brain region that acts like a built-in focus filter, helping the brain ignore distractions and zero in on what matters most. When ...
June 24, 2026 Scientists have uncovered a surprising new twist in what happens when cells die. As dying cells break apart, they leave behind tiny “footprints of ...
June 24, 2026 A study of nearly 300 people across northern Britain found that vitamin D levels often stay low all year in groups most at risk. Surprisingly, summer sunshine did not significantly boost vitamin D ...
June 23, 2026 Scientists found that one tiny genetic change can completely alter how a coronavirus behaves in different species. Comparing SARS-CoV-2 with a closely related bat-only virus, they showed that a ...
June 23, 2026 Scientists discovered that kombucha’s flavor, chemistry, and antioxidant activity vary dramatically depending on the tea used to make it. Green and oolong tea kombuchas emerged as the most ...