During mammalian embryogenesis, the first differentiation event that occurs leads to a polarization of the outer cells of the 16-cell morula. This outer layer of cells forms the trophectoderm and the inner, apolar clump of cells become the inner cell mass. The inner cell mass will give rise to:

the entire embryo

Explanation:

The trophectoderm refers to the polarized single cell layer that forms the wall of the blastocyst, thereby forming the first epithelium during embryogenesis. Moreover, the blastocyst is composed of 1-an inner cell mass (ICM) which will form all the tissues of the embryo's body, and 2-an outer layer composed of cells collectively called the trophoblast. The ICM of the blastocyst will form the embryoblast (which subsequently will give rise to the embryo itself) and the fetus, while the trophoblast will form all of the supporting tissues (i.e., amniotic sac, placenta, and umbilical cord). In humans, the blastocyst is the developmental stage of the embryo on day 5 after fertilization.

"1. it should be, it has been for about 20 years, and it's really not much different in the end than breeding animals to have particular traits. there are always concerns about genetically engineered animals/plants affecting the environment in unexpected negative ways, but i can't think of an example where the fears didn't turn out to be baseless.  

first, as you point out, it would be a great advance in pharmacology, to be able to tailor drugs and their doses to me. the pros involve better medical treatment. the cons involve privacy issues like insurance companies denying coverage to people with genetic risk factors. looking at dna markers wouldn't affect the frequency of genetic diseases, but it would allow detection of them earlier. and ok, actually i suppose that if people used this information to avoid having children with genetic diseases, some might decrease in frequency."

a. by using fur or clothes to trap heat energy near the body