Bones aren't uniformly red inside; the redness comes from red bone marrow, a vital tissue found within the cavities of certain bones.
What is Red Bone Marrow?
Red bone marrow is a soft, spongy tissue located within the larger bones of the body, such as the pelvis, scapula (shoulder blade), skull, and sternum (breastbone). My.ClevelandClinic Its primary function is hematopoiesis, the process of creating blood cells. This crucial tissue contains hematopoietic stem cells, which are responsible for generating:
- Red blood cells (erythrocytes) carrying oxygen throughout the body.
- White blood cells (leukocytes) essential for immune function and fighting infection.
- Platelets (thrombocytes) vital for blood clotting.
The presence of these blood cells gives red bone marrow its characteristic reddish hue. It's important to note that not all bones contain red bone marrow; some contain yellow bone marrow, primarily composed of fat cells.
Why Don't We See Red Staining on Bones After Death?
The misconception that bones are uniformly red might stem from a misunderstanding of blood's location within the body. As noted in a Reddit discussion https://www.reddit.com/r/AskReddit/comments/etvk1a/why_arent_bonesskeletons_stained_red_from_being/, blood generally circulates within arteries, veins, and capillaries. It's not pooled within the bone structure itself in a way that would cause significant staining after death. The red color observed in living bone is internal, originating from the bone marrow.
Red Color in Cooked Chicken
Sometimes, a red color may be observed in cooked chicken bones. This isn't necessarily blood pooling, but can be attributed to several factors including myoglobin (a protein that stores oxygen in muscle tissue) and other pigments. A Quora discussion https://www.quora.com/After-cooking-chicken-legs-and-then-after-eating-them-Ive-noticed-that-there-is-a-blood-colored-liquid-on-the-bone-mostly-Which-is-probably-blood-What-else-could-it-be-Is-this-going-to-cause-me-to-become-sick mentions that some residual blood can be present in the marrow, but it is unlikely to be a significant amount.
