Strep throat is a contagious disease caused by infection with streptococcal bacteria, which causes inflammation and swelling of the mucous membranes lining the back of the throat and the tonsils.trep throat is a contagious disease caused by infection with streptococcal bacteria, which causes inflammation and swelling of the mucous membranes lining the back of the throat and the tonsils.
Once an egg cell is fertilized by a sperm, it will divide and become an embryo. In the embryo, there are stem cells that are capable of becoming all of the various cell types of the human body. For research, scientists get embryos in two ways. Many couples conceive by the process of in vitro fertilization. In this process, a couple's sperm and eggs are fertilized in a culture dish.
Though some experiments have shown that adult stem cells can be useful, the most promising results come from embryonic stem cells derived from a 5-7 day embryo and embryonic germ cells, derived from aborted fetuses. Each of the sources of stem cells poses its own ethical questions.dult tissues also contian stem cells, ulike that of the embryonic stem cells and embryonic germ cells these are generally multipotent and only develop into cells of a specific tissue or organ type. These cells are in many types of adult tissues to replenish cells that wear out.