Life Begins at Fertilization
The following references illustrate the fact that a new human embryo, the starting point for a human life, comes into existence with the formation of the one-celled zygote:
“Development of the embryo begins at Stage 1 when a sperm fertilizes an oocyte and together they form a zygote.”
[England, Marjorie A. Life Before Birth. 2nd ed. England: Mosby-Wolfe, 1996, p.31]
"Human development begins after the union of male and female gametes or germ cells during a process known as fertilization (conception).
“Fertilization is a sequence of events that begins with the contact of a sperm (spermatozoon) with a secondary oocyte (ovum) and ends with the fusion of their pronuclei (the haploid nuclei of the sperm and ovum) and the mingling of their chromosomes to form a new cell. This fertilized ovum, known as a zygote, is a large diploid cell that is the beginning, or primordium, of a human being.”
[Moore, Keith L. Essentials of Human Embryology. Toronto: B.C. Decker Inc, 1988, p.2]
“Embryo: the developing organism from the time of fertilization until significant differentiation has occurred, when the organism becomes known as a fetus.”
[Cloning Human Beings. Report and Recommendations of the National Bioethics Advisory Commission. Rockville, MD: GPO, 1997, Appendix-2.]
“Embryo: An organism in the earliest stage of development; in a man, from the time of conception to the end of the second month in the uterus.”
[Dox, Ida G. et al. The Harper Collins Illustrated Medical Dictionary. New York: Harper Perennial, 1993, p. 146]
“Embryo: The early developing fertilized egg that is growing into another individual of the species. In man the term ‘embryo’ is usually restricted to the period of development from fertilization until the end of the eighth week of pregnancy.”
[Walters, William and Singer, Peter (eds.). Test-Tube Babies. Melbourne: Oxford University Press, 1982, p. 160]
“The development of a human being begins with fertilization, a process by which two highly specialized cells, the spermatozoon from the male and the oocyte from the female, unite to give rise to a new organism, the zygote.”
[Langman, Jan. Medical Embryology. 3rd edition. Baltimore: Williams and Wilkins, 1975, p. 3]
“Embryo: The developing individual between the union of the germ cells and the completion of the organs which characterize its body when it becomes a separate organism… At the moment the sperm cell of the human male meets the ovum of the female and the union results in a fertilized ovum (zygote), a new life has begun… The term embryo covers the several stages of early development from conception to the ninth or tenth week of life.”
[Considine, Douglas (ed.). Van Nostrand’s Scientific Encyclopedia. 5th edition. New York: Van Nostrand Reinhold Company, 1976, p. 943]
“I would say that among most scientists, the word ‘embryo’ includes the time from after fertilization…”
[Dr. John Eppig, Senior Staff Scientist, Jackson Laboratory (Bar Harbor, Maine) and Member of the NIH Human Embryo Research Panel – Panel Transcript, February 2, 1994, p. 31]
“The development of a human begins with fertilization, a process by which the spermatozoon from the male and the oocyte from the female unite to give rise to a new organism, the zygote.”
[Sadler, T.W. Langman’s Medical Embryology. 7th edition. Baltimore: Williams & Wilkins 1995, p. 3]
