1.
Embryonic stem
cells - are harvested from the inner cell mass of the
blastocyst seven to ten days after fertilization.
2.
Fetal stem cells - are taken from the germline tissues that will make up
the gonads of aborted fetuses.
3.
Umbilical cord
stem cells - Umbilical cord blood contains stem cells similar to
those found in bone marrow.
4.
Placenta derived
stem cells - up to ten times as many stem cells can be harvested
from a placenta as from cord blood.
5.
Adult stem cells - Many adult tissues contain stem cells that can be
isolated.