Scientific Source #58 – Medical Textbook
“Human development is a continuous process that begins when an oocyte (ovum) from a female is fertilized by a sperm (spermatozoon) from a male. Cell division, cell migration, programmed cell death, differentiation, growth, and cell rearrangement transform the fertilized oocyte, a highly specialized, totipotent cell, a zygote, into a multicellular human being.”58
58Moore, K.L., The Developing Human: Clinically Oriented Embryology, 8th ed., Philadelphia: Saunders, 2007. p. 2.