A sex chromosome in certain animals, such as chickens, turkeys, and moths. In humans, males are XY and females XX, but in animals with a Z chromosome, males are ZZ and females are WZ.
Also called Brill-Zinsser disease, recrudescence of epidemic typhus years after the initial attack.
The strong membrane that forms around an ovum as it develops in the ovary. The membrane remains in place during the egg's travel through the fallopian tube.
An abnormal and persistent fear of animals.
The cell formed by the union of a male sex cell (a sperm) and a female sex cell (an ovum). The zygote develops into the embryo.
The bone that forms the prominence of the cheek.
Stands for zygote intrafallopian transfer, a method used to treat infertility in which an egg fertilized in vitro (outside the body) is placed into a woman's fallopian tube.