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.

Zeta-chain-associated protein kinase 70. A member of the protein tyrosine kinase family, ZAP-70 is normally expressed in T cells and natural killer cells and has a critical role in the initiation of T-cell signaling. ZAP-70 is expressed in T cells and tumors of T-cell lineage. A high level of ZAP-70 expression appears restricted to T-cell […]

‘When you hear hoof beats, think of horses, not zebras.’ For example, when someone develops a mild transient cough, a virus infection is the most logical and likely cause, and tuberculosis is a zebra.

A gene that is lethal (fatal) for the zygote, the cell formed by the union of a sperm (male sex cell) and an ovum (female sex cell). The zygote would normally develop into an embryo, as instructed by the genetic material within the unified cell. However, a zygotic lethal gene scotches prenatal development at its […]

A technique in which a woman’s egg is fertilized outside the body, then implanted in one of her fallopian tubes. This technique is one of the methods used to overcome infertility, the inability of couples to produce offspring on their own. First, the egg and the male sperm needed to fertilize it are harvested. Then […]

Cor: The Latin word for the heart. For example, cor pulmonale is heart disease that results from abnormally high resistance to the passage of blood through the lungs. Cor biloculare is a two-chambered heart resulting from failure of development of the walls that normally separate the two atria from each other and separate the two […]

Elective: In medicine, something chosen (elected). An elective procedure is one that is chosen (elected) by the patient or physician that is advantageous to the patient but is not urgent. Elective surgery is decided by the patient or their doctor. The procedure is seen as beneficial but not absolutely essential at that time.

Abnormal dryness of the skin, mucous membranes, or conjunctiva (xerophthalmia). There are many causes of xerosis, and treatment depends on the particular cause.

Encapsulated: Confined to a specific area. For example, an encapsulated tumor remains in a compact form.

Chasing the dragon: A practice of heroin use involving heating heroin and then inhaling it. Some heroin users have gone to this practice because they believe erroneously that it will protect them against contracting HIV and other diseases associated with injecting heroin. “Chasing the dragon” carries a risk of untreatable brain damage with death occurring […]