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 […]

In dentistry, a molar is one of the posterior teeth well adapted to grinding, in keeping with its origin from the Latin mola meaning millstone.

Pertaining to the skeleton, the bones of the body that collectively provide the frame for the body.

The donation or sale of blood plasma for use in medical or other products. Unlike blood donors, most plasma donors in the US are paid. The procedure is done in a walk-in facility, where whole blood is taken through an IV needle and separated into plasma and blood cells. The blood cells are then returned […]

The birth of a dead baby, the delivery of a fetus that has died before birth for which there is no possibility of resuscitation. The distinction between a stillbirth and a miscarriage is arbitrary. The dividing line has variously set at 20 to 24 weeks of gestation or at a specific weight, such as 500g. […]

from sitting to standing or from lying down to sitting or standing. Postural hypotension is more common in older people. The change in position causes a temporary reduction in blood flow and therefore a shortage of oxygen to the brain. This leads to lightheadedness and, sometimes, a “black out” episode, a loss of consciousness. Tilt-table […]