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 […]

A precursor (forerunner) of a drug. A prodrug must undergo chemical conversion by metabolic processes before becoming an active pharmacological agent. For example, sulfasalazine is a prodrug. It is not active in its ingested form. It has to be broken down by bacteria in the colon into two products — 5-aminosalicylic acid (5ASA) and sulfapyridine […]

A common mild rash of unknown origin that can appear on a person of any age (most commonly at 10-35 years of age). It may last from several weeks to a few months, often begins with a “herald” patch, a large single pink patch on the chest or back and, within a week or so, […]

Arteritis, cranial: A serious disease characterized by inflammation of the walls of the blood vessels (vasculitis). The vessels affected are the arteries (hence the name “arteritis”). The age of affected patients is usually over 50 years of age. Cranial arteritis is also known as temporal arteritis and as giant cell arteritis. It can lead to […]

Within the peritoneal cavity, the area that contains the abdominal organs.

The study of malaria. Someone who is versed in malariology is a malariologist.