Dictionary

nullipara A woman who has not given birth to a viable child.

nucleus 1 In cell biology, the structure that houses the chromosomes. 2 In neuroanatomy, a group of nerve cells.

nucleotide A subunit of DNA or RNA that consists of a nitrogenous base (A, G, T, or C in DNA; A, G, U, or C in RNA), a phosphate molecule, and a sugar molecule (deoxyribose in DNA, and ribose in RNA). Thousands of nucleotides are linked to form a DNA or an RNA molecule.

nucleosome A structure that is responsible in part for the compactness of a chromosome. Each nucleosome consists of a sequence of DNA wrapped around a core of histone, which is a type of protein.

nucleic acid One of the family of large molecules that includes deoxyribonucleic acid (DNA) and ribonucleic acid (RNA). Nucleic acids were so named because they were first found in the nucleus of cells, but they have since been discovered to also exist outside the nucleus. See also DNA; RNA.

nuclear medicine The branch of medicine concerned with the use of radioisotopes in the diagnosis, management, and treatment of disease.

nuchal fold scan A prenatal ultrasound test that is done to screen for chromosome disorders such as Down syndrome and Turner syndrome. The scan measures the size of the space behind the neck of the fetus between 10 and 14 weeks of pregnancy and provides an index of the amount of fluid that has accumulated…

nuchal Referring to the back of the neck (nape). For example, nuchal rigidity is a stiff neck, sometimes a symptom of meningitis.

NTD Neural tube defect.

NSE test Neuron-specific enolase test.

NSAID Nonsteroidal anti-inflammatory drug, a medication that is commonly prescribed or purchased over the counter to treat the inflammation associated with conditions such as arthritis, tendonitis, and bursitis. Examples of NSAIDs include aspirin, indomethacin (brand name: Indocin), ibuprofen (brand name: Motrin), naproxen (brand name: Naprosyn), piroxicam (brand name: Feldene), and nabumetone (brand name: Relafen). People…

NS Noonan syndrome.