Where do embryonic type stem cells come from?
• Embryos – Embryonic stem cells are obtained by harvesting living embryos which are generally 5-7 days old. The removal of embryonic stem cells invariably results in the destruction of the embryo. • Fetuses – Another kind of stem cell, called an embryonic germ cell, can be obtained from either miscarriages or aborted fetuses. Where do adult type stem cells come from? • Umbilical Cords, Placentas and Amniotic Fluid – Adult type stem cells are derived from various pregnancy-related tissues. • Adult Tissues – In adults, stem cells are present within various tissues and organ systems. These include the bone marrow, liver, epidermis, retina, skeletal muscle, intestine, brain, dental pulp, and elsewhere. Even fat obtained from liposuction has been shown to contain significant numbers of adult type stem cells. • Cadavers – Neural stem cells have been removed from specific areas in post-mortem human brains as late as 20 hours following death. How do embryonic and adult stem cells compare? Emb
