Embryos and Fetuses in Research

Embryos and Fetuses in Research

The main difference between the inner cell mass of day 14 and day 22 is that the inner cell mass at day 14 has the potential not only to form any human body cell, but can also become an entirely new embryonic cell mass. This phenomenon occurs during the unaided process of twinning, when the fertilized egg splits exactly in half to form two or more identical embryos. However, on day 22, the cardiac cells of the embryonic cell mass first begin to beat, signifying the first heart beat.

A certain degree of self-sufficiency needs to be established before an embryo or fetus can be afforded the same rights and considerations as a person. During much of its development, the embryo is a collection of cells. While powerful, this cellular mass contains few if any human characteristics. No less remarkable than the cellular masses that form any other living creature, the embryo in early stages of development cannot be considered a human being. Even at day 22, when the primitive heart forms more fully, the embryo should not be afforded the rights and privileges of a human being because the heart cells are not fully formed, let alone the rest of the body. When the brain becomes more fully developed and the fetus is finally capable of surviving outside of the mother's body -- with or without intensive medical care -- then it can be afforded the status of a fully formed human with all attendant rights and privileges.