Stem cells are found in various parts of the body, both in embryos and adults, as well as in some perinatal tissues:

• Adult stem cells are located in many tissues including brain, bone marrow, blood vessels, skin, teeth, heart, liver, muscle, and fat (adipose tissue). They exist in small numbers within these tissues and serve to maintain and repair them

• Bone marrow is a major source of hematopoietic stem cells, which produce blood cells

• Skin contains epidermal stem cells that help regenerate the epidermis

• Intestinal crypts house intestinal stem cells responsible for renewing the intestinal lining

• Umbilical cord blood and placenta after birth provide stem cells that are more primitive and have broad regenerative potential

• Amniotic fluid and dental pulp (baby teeth) also contain stem cells with potential for multiple cell types

• Specific niches in organs such as bone marrow or gonads harbor adult stem cells that replenish tissues

• Induced pluripotent stem cells (iPSCs) are adult cells reprogrammed in the lab to behave like embryonic stem cells, but naturally, embryonic stem cells are found in early-stage embryos (blastocysts)

In summary, stem cells are widely distributed in the body, primarily in bone marrow, blood, skin, fat, brain, liver, muscle, and perinatal tissues like umbilical cord and amniotic fluid, where they function to regenerate and repair tissues