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 […]

1441-1442.) This study was not large enough to prove a link between Ecstasy and birth defects, but these initial findings indicate that Ecstasy should be avoided by pregnant women.

The enzyme encoded in the HGD gene. Mutation of HGD causes the genetic disease alkaptonuria. Homogentisate oxidase is also called Homogentisate 1,2-dioxygenase .

A long polysyllabic word that means having many syllables or using long words. From the Latin sesqui- meaning one and a half times + ped, pes meaning foot. In Ars Poetica, the Roman poet Horace cautioned young poets against using “sesquipedalia verba” — “words a foot and a half long.” For example, Pneumonoultramicroscopicsilicovolcanosconiosis.

In transplantation biology, when the body’s immune system attacks transplanted cells, tissues, or organs. For example, a transplanted kidney may be rejected.

Neutrophils have “neutral” subtle granules; Eosinophils have prominent granules that stain readily with the acid dye eosin; and Basophils have prominent granules that stain readily basic (nonacidic) dyes. This classification dates back to a time when certain structures could be identified in cells by histochemistry, but the functions of these intracellular structures were still not […]