X Chromosome — The congenital, developmental, or genetic information in the cell that transmits the information necessary to make a female. All eggs contain one X chromosome, and half of all sperm carry an X chromosome. When two X chromosomes combine, the baby will be a girl.
Y Chromosome — The genetic material that transmits the information necessary to make a male. The Y chromosome can be found in one-half of the man’s sperm cells. When an X and a Y chromosome combine, the baby will be a boy.
Zona Pellucida — The protective outer membrane surrounding the egg.
Zygote — A fertilized egg which has not yet divided.
Zygote Intrafallopian Transfer (ZIFT) — An ART in which eggs are removed from a woman’s ovaries, fertilized with the man’s sperm in a lab dish, and the resulting Zygotes are transferred into the woman’s fallopian tubes during a minor surgical procedure.