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
May 11, 2026
May 11, 2026 An ancient Chinese exercise routine may be just as powerful as a daily brisk walk for lowering blood pressure — without equipment, gyms, or intense workouts. In a major clinical trial, adults with stage 1 hypertension who practiced baduanjin, a ...
May 11, 2026 Researchers say fructose is not just “empty calories” — it may actively push the body toward fat storage and metabolic disease. A new review found that fructose affects the body differently ...
May 11, 2026 A new international analysis suggests there may be a surprisingly simple secret to keeping weight off after dieting: walking about 8,500 steps a day. Researchers found that people who boosted their daily steps to around that level during a ...
May 11, 2026 A major new analysis suggests semaglutide (Ozempic, Wegovy) works remarkably well in adults over 65, helping many lose substantial amounts of weight while improving heart and metabolic health. Participants taking the drug lost over 15% of their body ...
May 10, 2026 Ultra-processed foods may be doing far more damage than many people realize. A major new European cardiology report warns that people who eat the most ultra-processed foods face significantly higher ...
May 10, 2026 Scientists at the University of Rochester pulled off a remarkable experiment: they transferred a longevity-related gene from the famously long-lived naked mole rat into mice, and the mice ended up healthier and lived longer. The special gene boosts ...
May 10, 2026 Scientists have uncovered a hidden “stop-scratching” signal in the nervous system that tells your brain when enough scratching is enough. The discovery centers on a molecule called TRPV4, which acts like part of an internal braking system for ...
May 9, 2026 Rebooting the gut microbiome with bacteria from youth may help stop aging-related liver damage and even prevent liver cancer, according to new research in mice. Older mice that received their own preserved youthful microbiome showed less ...
May 9, 2026 Researchers have developed a stem cell-based model of the human intestine that may transform how new IBD treatments are discovered. After testing thousands of compounds, they identified glycyrrhizin — a natural substance found in black licorice ...
May 9, 2026 A new study shows that listening to your own favorite workout music can dramatically boost endurance. Cyclists exercising with self-selected songs lasted nearly 20% longer than when riding in silence, yet they didn’t feel more exhausted at the ...
May 9, 2026 Scientists studying axolotls, zebrafish, and mice have uncovered a shared set of genes that may one day help humans regrow lost limbs. By identifying powerful “SP genes” involved in regeneration, ...
May 8, 2026 Scientists have uncovered a surprising secret hidden inside fat cells that could reshape how we think about obesity and metabolic disease. A protein called HSL, long believed to simply release stored fat when the body needs energy, turns out to have ...
Latest Headlines
updated 12:56 pm ET
May 8, 2026 A common constipation drug may have unexpectedly unlocked a new way to slow chronic kidney disease — a condition that affects millions and often leads to dialysis. In a clinical trial involving 150 ...
May 8, 2026 Scientists have uncovered a surprising way to influence the bacteria living in our mouths — not by killing them, but by interrupting how they ...
May 8, 2026 Beneath the beauty of coral reefs lies a hidden universe of microbes unlike anything scientists expected. Each coral species supports its own ...
May 7, 2026 Many cancer patients turn to biotin supplements hoping to restore hair lost during treatment, but experts warn the popular vitamin may do more harm than good. While biotin is often marketed for ...
May 7, 2026 A little-known tree from Brazil’s Atlantic Forest may hold a surprising weapon against COVID-19. Researchers discovered that compounds called galloylquinic acids, extracted from its leaves, can ...
May 7, 2026 Eating eggs might do more than just start your day—it could help protect your brain. Researchers found that people 65 and older who eat eggs regularly have a significantly lower risk of developing ...
May 7, 2026 Researchers have created a next-generation obesity drug that works like a “Trojan horse,” using GLP-1/GIP signals to slip a powerful metabolic enhancer directly into target cells. In mice, it ...
May 7, 2026 Some people taking Ozempic-like diabetes drugs may be getting dramatically better results for a surprising reason: why they overeat in the first place. A year-long study in Japan found that people ...
May 7, 2026 Aging doesn’t just add fat—it redistributes it in risky ways, pushing more into the abdomen where it can harm health. Scientists found that testosterone plays a key role in this shift. In older ...
May 6, 2026 Scientists in Sweden have taken a major step toward a potential cure for type 1 diabetes by developing a more reliable way to create insulin-producing cells from human stem cells. These lab-grown ...