Bone marrow
Bone marrow was a biological tissue found within the larger bones of many species. Generally, bone marrow produced oxygen-carrying blood s (erythrocytes), among other types, or cells that could become fat, cartilage, or bone.

In 2267, Pavel Chekov was subjected to a variety of medical tests, including sampling of his bone marrow, following the discovery of his apparent immunity to the radiation which caused rapid aging of all members of a landing party except him. () 

In 2371, Kes discovered the genetic markers in Seska's blood did not match that of a Bajoran, but rather appeared to be Cardassian. When confronted with this evidence by Chakotay, Seska claimed to have survived an outbreak of Orkett's disease due to a bone marrow transplant from a sympathetic Cardassian woman named Kattell. However, The Doctor knew that a bone marrow transplant could not explain the genetic markers, and Seska was exposed as a Cardassian spy. ()

In 2372, Vidiians who were invading a duplicate of Voyager extracted Kes' pelvic ridge in order to analyze her bone marrow for resistance to the phage. ()

In 2374, The Doctor noted high concentrations of Borg organelles in Seven of Nine's bone marrow and lymphatic tissue. ()

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Bones