• Z chromosome

    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.

  • ZAP-70

    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 […]

  • Zebra

    ‘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.

  • Zygotic lethal gene

    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 […]

  • Zygote intrafallopian transfer (ZIFT)

    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 […]

  • Autosomal chromosome

    Autosomal chromosome: Any chromosome except for the sex chromosomes. Humans have 44 autosomal chromosomes, or autosomes.

  • Breast augmentation

    Artificial enlargement of the breasts. Breast augmentation may be done by insertion of a silicone bag (prosthesis) under the breast (submammary) or under the breast and chest muscle (subpectoral), after which the bag is filled with saline solution. This prosthesis expands the breast area to give the appearance of a fuller breast (increased cup size).

  • Anterior cruciate ligament

    Anterior cruciate ligament: A ligament in the knee that crosses from the underside of the femur (the thigh bone) to the top of the tibia (the bigger bone in the lower leg). Abbreviated ACL. Injuries to the ACL can occur in a number of situations, including sports, and can be quite serious, requiring surgery. The […]

  • Sarcoma, metastatic

    A sarcoma that is spreading into other body tissues through the lymphatic system. The most common site for metastatic sarcoma is the lungs, and there are usually multiple lesions (seen as spots on an X-ray, or as masses on a CT scan). Treatment is by chemotherapy and surgery, but prognosis is poor.

  • DNA, nongenetic

    DNA, nongenetic: Through the marvelous medium of the Internet, we have discovered that DNA need not refer to deoxyribonucleic acid. Specifically, in an e-mail entitled ” A day in the life of a specialist registrar” from Glascow, Scotland we read that in gynecology outpatient clinic, the specialist registrar (resident in the U.S.) at “12:10 Sorted […]