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
April 17, 2026
Apr. 17, 2026 Scientists have uncovered a surprising twist in how bacteria share genes—including those that spread antibiotic resistance. Tiny virus-like particles called gene transfer agents (GTAs), once ...
Apr. 17, 2026 Sparkling water is often seen as a simple, healthy drink—but could it also help with weight loss? New research suggests it may slightly boost how the body processes blood sugar and energy. However, the effect is very small, meaning it’s no ...
Apr. 16, 2026 A hormone called FGF21 can reverse obesity in mice by activating a newly identified brain circuit tied to metabolism. Surprisingly, it works in the hindbrain—the same region targeted by GLP-1 drugs like Ozempic and Wegovy—but through a ...
Apr. 16, 2026 Researchers have found a way to make cancer-killing immune cells more powerful and precise. By adding specific signaling components, they boosted the cells’ readiness to attack tumors. Surprisingly, briefly suppressing the cells with a drug before ...
Apr. 16, 2026 Scientists have discovered that a protein linked to cell death is secretly driving the aging of blood stem cells in a completely different way. Instead of killing the cells, it damages their mitochondria, sapping their energy and weakening the ...
Apr. 16, 2026 A rogue set of “zombie” immune cells may be driving aging and fatty liver disease by flooding tissues with inflammation. Researchers found these cells accumulate with age and high cholesterol—and can make up most of the liver’s immune cells ...
Apr. 16, 2026 A massive, nearly 20-year study tracking over 650,000 Americans with irritable bowel syndrome is raising new questions about the long-term safety of common treatments. Researchers found that some widely used medications—including antidepressants ...
Apr. 16, 2026 New research suggests that aiming for a lower blood pressure target may deliver bigger heart health benefits than previously thought. Using large datasets and simulation models, scientists found that keeping systolic blood pressure below 120 mm Hg ...
Apr. 16, 2026 A massive Swedish study shows that AI can spot people at higher risk of melanoma using routine health data. Advanced models significantly outperformed basic methods, identifying high-risk groups with striking accuracy. Some individuals flagged by ...
Apr. 15, 2026 A surprising discovery from high-altitude animals like yaks and Tibetan antelopes could reshape how we treat nerve damage in humans. Scientists found that a genetic mutation helping these animals survive low-oxygen environments also protects and ...
Apr. 15, 2026 A surprising new clinical trial has revealed that metformin—a cheap, century-old drug widely used for type 2 diabetes—may help people with type 1 diabetes in an unexpected way. While researchers initially hoped it would reduce insulin ...
Apr. 15, 2026 A lifetime of mental stimulation—like reading, writing, and learning new skills—may help protect the brain as we age. People with the highest levels of cognitive enrichment had a much lower risk of Alzheimer’s and experienced symptoms years ...
Latest Headlines
updated 12:56 pm ET
Apr. 15, 2026 Scientists have taken a major step toward stopping Epstein-Barr virus (EBV), an extremely common infection linked to cancer and chronic disease. By ...
Apr. 14, 2026 A major new study reveals that treating gout may do far more than ease painful joint flare-ups—it could also protect the heart. Researchers found that patients who took common gout medications like ...
Apr. 14, 2026 Bread and other carbohydrate staples may be doing more than just filling plates—they could be quietly reshaping metabolism. In a surprising twist, researchers found that mice strongly preferred ...
Apr. 14, 2026 Scientists have discovered a way to supercharge the immune system’s T cells by blocking a protein called Ant2, forcing the cells to rewire how they generate energy. This shift makes them more ...
Apr. 13, 2026 Mitochondria don’t just generate energy—they also carefully organize their own DNA in a surprisingly elegant way. Scientists have discovered that ...
Apr. 13, 2026 Spending time with close companions might do more than strengthen bonds—it could also reshape your gut bacteria. In a study of island birds, those with stronger social ties shared more gut ...
Apr. 13, 2026 Public restrooms might seem like a germ nightmare, but the real risks aren’t always where you think. While toilet seats can carry bacteria, viruses, and even parasite traces, studies show they’re ...
Apr. 13, 2026 Scientists have developed a new way to fight gum disease without wiping out the mouth’s helpful bacteria—a major shift from traditional treatments. Instead of killing everything, this targeted ...
Apr. 13, 2026 New research reveals that obesity affects men and women in surprisingly different ways. Men are more likely to develop harmful abdominal fat and signs of liver stress, while women show higher ...
Apr. 13, 2026 For years, scientists believed our lifespan was mostly shaped by environment and chance, with genetics playing only a minor role. But a new study ...