![]() Gametogenesis refers to the maturation of germ cells, resulting in gametes. The product of fertilization is a living human being with 46 chromosomes. The products of gametogenesis are mature sex gametes with only 23 instead of 46 chromosomes. It may help to keep in mind that the products of gametogenesis and fertilization are very different. To accurately see why a sperm or an oocyte are considered as only possessing human life, and not as living human beings themselves, one needs to look at the basic scientific facts involved in the processes of gametogenesis and of fertilization. This is necessary so that after their fusion at fertilization the characteristic number of chromosomes in a single individual member of the human species (46) can be maintained-otherwise we would end up with a monster of some sort. 1 Sperms and oocytes are derived from primitive germ cells in the developing fetus by means of the process known as "gametogenesis." Because each germ cell normally has 46 chromosomes, the process of "fertilization" can not take place until the total number of chromosomes in each germ cell are cut in half. Even the early germ cells contain 46 chromosomes it is only their mature forms - the sex gametes, or sperms and oocytes - which will later contain only 23 chromosomes each. Every somatic (or, body) cell in a human being has this characteristic number of chromosomes. (The number can vary only slightly if the organism is to survive.) For example, the characteristic number of chromosomes for a member of the human species is 46 (plus or minus, e.g., in human beings with Down’s or Turner’s syndromes). To understand this, it should be remembered that each kind of living organism has a specific number and quality of chromosomes that are characteristic for each member of a species. During the process of fertilization, the sperm and the oocyte cease to exist as such, and a new human being is produced. 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. 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 (a single-cell embryonic human zygote). ![]() They are direct quotes and references from some of the most highly respected human embryology textbooks, and represent a consensus of human embryologists internationally. Please note that the scientific facts presented here are not simply a matter of my own opinion. Further, more complicated, details can be obtained by investigating any well-established human embryology textbook in the library, such as some of those referenced below. This would include such basic terms as: "gametogenesis," "oogenesis," "spermatogenesis," "fertilization," "zygote," "embryo," and "blastocyst." Only brief scientific descriptions will be given here for these terms. Getting a handle on just a few basic human embryological terms accurately can considerably clarify the drastic difference between the "scientific" myths that are currently circulating, and the actual objective scientific facts. In the final section, I will also address some "scientific" myths that have caused much confusion within the philosophical discussions on "personhood." At least it will clarify what the actual international consensus of human embryologists is with regard to this relatively simple scientific question. The purpose of this article is to focus primarily on a sampling of the "scientific" myths, and on the objective scientific facts that ought to ground these discussions. If the "science" used to ground these various discussions is incorrect, then any conclusions will be rendered groundless and invalid. Current discussions on abortion, human embryo research (including cloning, stem cell research, and the formation of mixed-species chimeras), and the use of abortifacients involve specific claims as to when the life of every human being begins. The question as to when a human person begins is a philosophical question. The question as to when the physical material dimension of a human being begins is strictly a scientific question, and fundamentally should be answered by human embryologists-not by philosophers, bioethicists, theologians, politicians, x-ray technicians, movie stars, or obstetricians and gynecologists. ( International Journal of Sociology and Social Policy 1999, 19:3/4:22-36 (in press)
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