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 gland within the male reproductive system that is located just below the bladder. Chestnut shaped, the prostate surrounds the beginning of the urethra, the canal that empties the bladder. The prostate is actually not one but many glands, 30-50 in number, between which is abundant tissue containing many bundles of smooth muscle. The secretion […]

Dysphagia: Difficulty swallowing. Dysphagia is due to abnormal nerve or muscle control. It is common, for example, after a stroke. Dysphagia can compromise nutrition and hydration and may lead to aspiration pneumonia and dehydration.

A machine with a moving strip on which one walks without moving forward. A treadmill was originally a wide wheel turned by the weight of people climbing on steps around its edge, used in the past to provide power for machines or as a punishment in prisons. The treadmill today serves as a device to […]

A basic type of chromosome rearrangement in which a segment that includes the centromere (and is therefore pericentric) is snipped out of a chromosome, inverted, and inserted back into the chromosome. The feature that makes it pericentric is that the breaks are on both sides of the centromere.

Fanconi anemia: A rare, inherited disease that adversely affects all the elements of bone marrow and is associated with malformations of the heart, kidney, and limbs, as well as pigmentary changes of the skin. Fanconi anemia predisposes a person to cancer, particularly to a disturbance of bone marrow growth called myelodysplasia and to acute myeloid […]