Scientific Source #139 – Medical Textbook
“[T]he 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.” 139
139 Hamilton, W. Boyd, & Mossman, H., Human Embryology 14 (4th ed. 1972), 14.