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.
1.2 Biology (Of a cell, part, or tissue) in the earliest stage of development: primordial germ cells. More example sentences. 1  Embryonic stem cells are primordial cells with the ability to morph into any type of cell in the body.2  During human fetal development, the primordial germ cells migrate to and are incorporated within the developing ovary and are termed oogonia. Embryonic stem cells are primordial cells with the ability to morph into any type of cell in the body. 2  During human fetal development, the primordial germ cells migrate to and are incorporated within the developing ovary and are termed oogonia.