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 […]

The ability of bacteria and other microorganisms to resist the effects of an antibiotic to which they were once sensitive. Antibiotic resistance is a major concern of overuse of antibiotics. Also known as drug resistance.

Epilepsy, Jacksonian:A brief alteration in movement, sensation or nerve function caused by abnormal electrical activity in a localized area of the brain. Seizures of this type typically cause no change in awareness or alertness. They are transient, fleeting, ephemeral. Jacksonian seizures are extremely varied and may involve, for example, apparently purposeful movements such as turning […]

A multiple subpial transection (MST) is a procedure is used to help control seizures that begin in areas of the brain that cannot be safely removed. The surgeon makes a series of shallow cuts (transections) in the brain tissue. These cuts interrupt the movement of seizure impulses but do not disturb normal brain activity, leaving […]

A reflex that is seen in normal newborn babies, who automatically turn the face toward the stimulus and make sucking (rooting) motions with the mouth when the cheek or lip is touched. The rooting reflex helps to ensure successful breastfeeding.

Anion: A negatively charged ion. Pronounced an-I-on. An anion is as opposed to a cation, which is a positively charged ion.