Scientific Source #4 – Medical Textbook
“Zygote. This cell, formed by the union of an oocyte and a sperm, is the beginning of a new human being.”4
4Moore, K.L. & Persaud, T.V.N., Before We Are Born: Essentials of Embryology and Birth Defects, 7th ed., Philadelphia: Saunders, 2008, p. 2.