>>123775028>"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]>"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]>"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]>"Zygote. This cell, formed by the union of an ovum and a sperm (Gr. zyg tos, yoked together), represents the beginning of a human being. The common expression 'fertilized ovum' refers to the zygote."
[Moore, Keith L. and Persaud, T.V.N. Before We Are Born: Essentials of Embryology and Birth Defects. 4th edition. Philadelphia: W.B. Saunders Company, 1993, p. 1]