Stem Cells - Brutes or Angels: Human Possibility in the Age of Biotechnology - page 42

fig. 2.5. normal developmental potential of a hemopoietic stem cell (hsC). hsCs
in the bone marrow or in umbilical cord blood are a type of adult stem cell. They
normally give rise to red blood cells, all of the cellular immune system (white blood
cells or leukocytes), and platelets, cell fragments involved in blood clotting.
stem cells is much more restricted than for esCs. normally, adult stem
cells only give rise to the cell types in the tissue where they reside, so they
are called multipotent instead of pluripotent.
The best-studied adult stem cell is the hemopoietic stem cell (hsC)
that replenishes the seven types of specialized hematic cells that populate
the blood and lymphatic systems (fig. 2.5). hematic cells include (1) red
blood cells that carry oxygen throughout the body; (2) five kinds of white
blood cells that fight viral, bacterial, and parasitic infections; and (3) the
megakaryocyte, a colossal cell that fragments into “minicells” called plate-
lets, required for blood clotting. hsCs are concentrated in the bone mar-
row and in blood from the umbilical cord and placenta, but even in these
tissues they account for only about one in ten thousand cells. some scien-
tists have tried to coax hsCs into becoming pluripotent like esCs without
much success.