Sci-Ed Fact: Each type of cell in the human body has its own life span. The following list indicates how long it takes for each type of cell to replace itself: -

Red blood cells ..................... 120-130 days White blood cells ........ 1 year Blood Platelets ...................... 10 days Bone cells ............................... 3 months Brain cells ............................... 90+ years Colon cells .............................. 4 days Liver cells ................................ 6 weeks Skin cells ................................. 1 month Stomach cells ......................... 5 days Spermatozoa cells ................ 3 days

(N.Y. Pub. Library Science Desk Ref.)