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 […]

Disease, Heberden: There are two different Heberden diseases: Angina pectoris, chest pain that is often severe and crushing, due to an inadequate supply of oxygen to the heart muscle. Osteoarthritis of the small joints with nodules (Heberden nodes) in and about the last joint of the finger. Both diseases were described by the respected English […]

A heart defect characterized by increased thickness (hypertrophy) of the wall of the left ventricle, the largest of the four chambers of the heart.

In anatomy, a horizontal plane passing through the standing body so that the transverse plane is parallel to the floor. For a more complete listing of terms used in medicine for spatial orientation, please see the entry to “Anatomic Orientation Terms”.

Esophageal speech: Speech produced with air that is trapped in the esophagus and forced out again.

A postmortem examination. Also known as necropsy.