What does the nature of death tell us about the beginning of human life? From the earliest stages of development, human embryos clearly function as organisms. Embryos are not merely collections of human cells, but living creatures with all the properties that define any organism as distinct from a group of cells; embryos are capable of growing, maturing, maintaining a physiologic balance between various organ systems, adapting to changing circumstances, and repairing injury. Mere groups of human cells do nothing like this under any circumstances. The embryo generates and organizes distinct tissues that function in a coordinated manner to maintain the continued growth and health of the developing body. Even within the fertilized egg itself there are distinct “parts” that must work together—specialized regions of cytoplasm that will give rise to unique derivatives once the fertilized egg divides into separate cells. Embryos are in full possession of the very characteristic that distinguishes a living human being from a dead one: the ability of all cells in the body to function together as an organism, with all parts acting in an integrated manner for the continued life and health of the body as a whole.
Linking human status to the nature of developing embryos is neither subjective nor open to personal opinion. Human embryos are living human beings precisely because they possess the single defining feature of human life that is lost in the moment of death—the ability to function as a coordinated organism rather than merely as a group of living human cells.
just so you know where i found this
http://print.firstthings.com/ftissue...es/condic.html
A. Basic human embryological facts
To begin with, scientifically something very radical occurs between the processes of gametogenesis and fertilization — the change from a simple part of one human being (i.e., a sperm) and a simple part of another human being (i.e., an oocyte — usually referred to as an "ovum" or "egg"), which simply possess "human life", to a new, genetically unique, newly existing, individual, whole living human being (an embryonic single-cell human zygote). That is, upon fertilization, parts of human beings have actually been transformed into something very different from what they were before; they have been changed into a single, whole human being. During the process of fertilization, the sperm and the oocyte cease to exist as such, and a new human being is produced.
theres tons of references in this one too...
http://www.vanderbilt.edu/SFL/dnirvi..._beginning.htm
different excerpts. all references named on website.
Also, note O'Rahilly's statement that the use of terms such as "ovum" and "egg" — which would include the term "fertilized egg" — is scientifically incorrect, has no objective correlate in reality, and is therefore very misleading — especially in these present discussions. Thus these terms themselves would qualify as "scientific" myths. The commonly used term, "fertilized egg," is especially very misleading, since there is really no longer an egg (or oocyte) once fertilization has begun. What is being called a "fertilized egg" is not an egg of any sort; it is a human being.
The fusion of the sperm (with 23 chromosomes) and the oocyte (with 23 chromosomes) at fertilization results in a live human being, a single-cell human zygote, with 46 chromosomes — the number of chromosomes characteristic of an individual member of the human species.