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
December 12, 2025
Dec. 12, 2025 A sweeping review of more than 2,500 studies reveals that despite booming public enthusiasm, cannabis has strong scientific support for only a few medical uses, leaving most popular claims—like relief for chronic pain, anxiety, and insomnia—on ...
Dec. 12, 2025 Scientists have uncovered a surprising link between dark chocolate and slower aging. A natural cocoa compound called theobromine was found in higher levels among people who appeared biologically younger than their real ...
Dec. 11, 2025 Researchers discovered that nerve injuries can alter the immune system throughout the body, and males and females react very differently. Male mice showed strong inflammatory responses, while females showed none, yet both transmitted pain-inducing ...
Dec. 11, 2025 Long COVID still affects people worldwide with stubborn symptoms like fatigue and cognitive issues. A clinical trial tested whether boosting NAD+ using nicotinamide riboside could help. Although overall group differences were limited, many ...
Dec. 11, 2025 Rats with naturally high stress levels were far more likely to self-administer cannabis when given access. Behavioral testing showed that baseline stress hormones were the strongest predictor of cannabis-seeking behavior. Lower cognitive flexibility ...
Dec. 11, 2025 Researchers found that both how often and how much someone drinks significantly shape their cancer risk, even at moderate levels. Vulnerability varies across groups, with genetics, socioeconomic status, obesity, and lifestyle behaviors amplifying ...
Dec. 11, 2025 Scientists discovered that the protein RPA plays a critical and previously unconfirmed role in stimulating telomerase to maintain long, healthy telomeres. When RPA malfunctions, telomeres can shorten dangerously, leading to serious ...
Dec. 11, 2025 A cutting-edge therapy using base-edited immune cells is offering a major breakthrough for patients with one of the toughest forms of blood cancer, T-cell acute lymphoblastic leukaemia. By precisely rewriting tiny sections of DNA, scientists at UCL ...
Dec. 11, 2025 Northwestern scientists have created the fastest-ever hepatitis C diagnostic, delivering accurate results in only 15 minutes. The test uses the DASH rapid PCR system, originally developed for COVID, but adapted for whole blood samples. Independent ...
Dec. 10, 2025 Scientists discovered that certain cancer cells use a low-level activation of a DNA-dismantling enzyme—normally seen in cell death—to survive treatment. Instead of dying, these “persister cells” leverage this sublethal signal to regrow. ...
Dec. 10, 2025 Obesity accelerates the rise of Alzheimer’s-related blood biomarkers far more rapidly than previously recognized. Long-term imaging and plasma data show that obese individuals experience much faster increases in proteins linked to ...
Dec. 10, 2025 Researchers discovered that a long-misunderstood protein plays a key role in helping chromosomes latch onto the right “tracks” during cell division. Instead of acting like a motor, it works more like a stabilizer that sets everything up ...
Latest Headlines
updated 12:56 pm ET
Dec. 10, 2025 A Virginia Tech study shows that ultra-processed foods may influence adolescents differently from slightly older young adults. Participants aged 18 to 21 ate more at a buffet and snacked even when ...
Dec. 10, 2025 New research is challenging one of medicine’s oldest assumptions: that cancer must be attacked to be cured. By treating glioblastoma patients with a simple combination of resveratrol and copper, ...
Dec. 10, 2025 Researchers discovered that unusually high temperatures can hinder early childhood development. Children living in hotter conditions were less likely to reach key learning milestones, especially in ...
Dec. 9, 2025 BISC is an ultra-thin neural implant that creates a high-bandwidth wireless link between the brain and computers. Its tiny single-chip design packs tens of thousands of electrodes and supports ...
Dec. 9, 2025 Microscopic fibers secretly shape how every organ in the body works, yet they’ve been notoriously hard to study—until now. A new imaging technique called ComSLI reveals hidden fiber orientations ...
Dec. 9, 2025 Most people worldwide aren’t getting enough omega-3, leaving a major gap between scientific recommendations and daily diets. Researchers emphasize the critical role of EPA and DHA across all life ...
Dec. 9, 2025 Researchers discovered that a tiny structural feature of the enzyme GPX4 helps keep neurons safe. A rare mutation removes this protection, allowing harmful molecules to damage cell membranes and ...
Dec. 8, 2025 Deep-brain recordings showed that Mounjaro and Zepbound briefly shut down the craving circuits linked to food noise in a patient with severe obesity. Her obsessive thoughts about food disappeared as ...
Dec. 8, 2025 Using less ipilimumab appears to make melanoma immunotherapy both safer and more effective, with dramatically better response and survival outcomes. The findings suggest that reducing side effects ...
Dec. 8, 2025 Researchers revealed that the microbial metabolite TMA can directly block the immune protein IRAK4, reducing inflammation and improving insulin sensitivity. The molecule counteracts damage caused by ...