Tyler LaMonte
Period B Engineering
5/11/18

What are stem cells ?

1. "An undifferentiated cell of a multicellular organism that is capable of giving rise to indefinitely more cells of the same type, and from which certain other kinds of cell arise by differentiation."

   
   

   
   

   

   
   

   Embryonic

   

   
   

   Embryonic stem cells are the cells of the inner cell mass of a blastocyst, an early-stage embryo. Human embryos "reach the blastocyst stage 4–5 days post fertilization, at which time they consist of 50–150 cells." ES cells are pluripotent and give rise during development to all derivatives of the three primary germ layers: ectoderm, endoderm and mesoderm.

   
   

   
   

   
   

   
   

   Fetal 

   
   

   The primitive stem cells located in the organs of fetuses are referred to as fetal stem cells. There are two types of fetal stem cells:

   1. "Fetal proper stem cells come from the tissue of the fetus proper, and are generally obtained after an abortion." These stem cells are not immortal but have a high level of division and are multipoint.
   2. "Extra embryonic fetal stem cells come from extraembryonic membranes, and are generally not distinguished from adult stem cells." These stem cells are acquired after birth, they are not immortal but have a high level of cell division, and are pluripotent.

   
   

   Adult 

   
   

   Adult stem cells, also called somatic stem cells, are stem cells which maintain and repair the tissue in which they are found. They can be found in children, as well as adults.
   
   
   
   
   
   
   

   

   
   
   
   
   
   
   
   
   
   
   Links
   
   https://stemcells.nih.gov/info/basics/1.htm
   https://medlineplus.gov/stemcells.html
   https://www.medicalnewstoday.com/info/stem_cell