Where in the body do we find adult stem cells, and are they in abundance?

Answer 1

The first place they were isolated (more than 50 years ago) was in the bone marrow - where they are the factory cells that produce all of the components of your blood, and others that make bones or cartilage. Since then, stem cells have been identified in several other tissues, from adipose tissue and mammary glands, to the lining of the nose - and recently including the brain. These particular cells, contrary to long-held belief, can apparently produce new brain cells, among other types of neural tissue.

Nowhere in the human body are adult stem cells particularly "abundant," but they do exist, and play a role in healing and limited regeneration of injured tissues. They are by far the most abundant and easiest to harvest in the bone marrow.