New! Sign up for our free email newsletter.
Reference Terms
from Wikipedia, the free encyclopedia

Bone marrow

Bone marrow is the tissue comprising the center of large bones. It is the place where new blood cells are produced. Bone marrow contains two types of stem cells: hemopoietic (which can produce blood cells) and stromal (which can produce fat, cartilage and bone). There are two types of bone marrow: red marrow (also known as myeloid tissue) and yellow marrow. Red blood cells, platelets and most white blood cells arise in red marrow; some white blood cells develop in yellow marrow. The color of yellow marrow is due to the much higher number of fat cells. Both types of bone marrow contain numerous blood vessels and capillaries.

At birth, all bone marrow is red. With age, more and more of it is converted to the yellow type. Adults have on average about 2.6kg (5.7lbs) of bone marrow, with about half of it being red. Red marrow is found mainly in the flat bones such as hip bone, breast bone, skull, ribs, vertebrae and shoulder blades, and in the cancellous ("spongy") material at the proximal ends of the long bones femur and humerus. Pink Marrow is found in the hollow interior of the middle portion of long bones.

There are several serious diseases involving bone marrow. In cases of severe blood loss, the body can convert yellow marrow back to red marrow in order to increase blood cell production.

The normal bone marrow architecture can be displaced by malignancies or infections such as tuberculosis, leading to a decrease in the production of blood cells and blood platelets. In addition, cancers of the hematologic progenitor cells in the bone marrow can arise; these are the leukemias.

Related Stories
 

Health & Medicine News

May 2, 2026
Boosting One Protein Helps the Brain Fight Alzheimer’s
May 2, 2026 — Scientists have discovered a way to help the brain clean itself of harmful Alzheimer’s plaques by activating its own support cells. By increasing a protein called Sox9, researchers were able to boost the activity of astrocytes, star shaped cells ...
Scientists Sound Alarm as Dangerous Amoebas Spread Globally
May 2, 2026 — Free-living amoebae are emerging as a global health concern, fueled by warming temperatures and outdated water systems. While many are harmless, some can cause deadly infections and even protect other dangerous microbes. Their ability to survive ...
Scientists Discover a Hidden Brain “Cleaning” Effect Triggered by Movement
May 1, 2026 — Scientists have uncovered a surprising link between simple body movement and brain health: every time you tighten your abdominal muscles—even slightly—your brain may gently sway inside your ...
You Don’t Need Intense Workouts to Build Muscle, New Study Reveals
May 1, 2026 — Building muscle doesn’t have to mean exhausting workouts or soreness. Researchers found that slow, controlled “lowering” movements can boost strength more efficiently while requiring less effort. Even five minutes a day of simple exercises ...
New Treatment Cuts Bad Cholesterol by Nearly 50% Without Statins
May 1, 2026 — A new breakthrough could change how high cholesterol is treated, offering a powerful alternative to traditional drugs. Researchers have developed tiny DNA-based molecules that shut down PCSK9—a key protein that keeps “bad” LDL cholesterol ...
Why Drinking More Water Didn’t Prevent Kidney Stones
May 1, 2026 — Kidney stones are notoriously painful—and frustratingly common, with many people facing repeat episodes. A massive new study tested whether a high-tech hydration program—complete with smart water bottles, reminders, coaching, and even financial ...
Your Gut Takes a “Double Hit” from Stress and Late-night Eating
May 1, 2026 — Chronic stress is already tough on your gut—but new research suggests late-night eating could make things even worse. Scientists analyzing thousands of people found that those under high stress who also ate a large portion of their calories after ...
Don’t Toss Cannabis Leaves: Scientists Found Rare Compounds with Medical Potential
May 1, 2026 — Scientists have uncovered a surprising new layer of complexity in Cannabis, identifying dozens of previously unknown compounds—including the first-ever evidence of rare molecules called ...
Surprising Obesity Discovery Rewrites Decades of Fat Metabolism Science
Apr. 30, 2026 — A key protein involved in fat metabolism has been found to do more than scientists once thought. Instead of just releasing fat, it helps maintain healthy fat tissue and balance in the body. When it’s missing or disrupted, the results can be ...
Scientists Restore Memory by Blocking a Single Alzheimer’s Protein
Apr. 30, 2026 — Researchers have identified a new potential weapon against Alzheimer’s: blocking a protein called PTP1B. In mice, this approach boosted memory and helped brain immune cells clear harmful plaque buildup. Since PTP1B is also linked to diabetes and ...
Scientists Reveal the Best Exercise for Knee Arthritis Pain Relief
Apr. 30, 2026 — A major review of 217 trials shows that aerobic exercise is the most effective option for managing knee osteoarthritis. Activities like walking, cycling, and swimming outperformed other exercise types in reducing pain and improving movement. While ...
A Hidden Map in Your Nose Could Explain How Smell Works
Apr. 30, 2026 — Scientists have finally cracked one of the biggest mysteries in the senses: how smell is organized. By mapping millions of neurons in mice, researchers discovered that smell receptors in the nose aren’t random at all—they’re arranged in neat, ...

Latest Headlines

updated 12:56 pm ET
more stories  

Breaking

this hour
this week

Strange & Offbeat Stories