“Bisexual reproduction is characteristic of all vertebrates, and gametogenesis (the production of germ cells) is its first phase. The next phase, the beginning of the development of a new individual, is the fusion of two germ cells (gametes) of different nature; one, the spermatozoon from the male parent; the other, the ovum from the female parent. The result of this fusion is the formation of the first cell of the new individual, the zygote.” 117
117 Hamilton, W. & Mossman, H., Human Embryology 14 (4th. ed 1972) (cited in The Human Life Bill: Report on S. 158 Before the Subcommittee on Separation of Powers of the Senate Committee on the Judiciary, 97th Cong., 1st Sess. (1981), p. 8).