Dictionary

internal radiation therapy See radiation therapy, internal.

international normalized ratio A system established by the World Health Organization (WHO) and the International Committee on Thrombosis and Hemostasis for reporting the results of blood coagulation (clotting) tests. Abbreviated INR. Under the INR system, all results are standardized. For example, a person taking the anticoagulant warfarin (brand name: Coumadin) would regularly have blood tested…

internist A physician who practices internal medicine and specializes in the diagnosis and medical treatment of adults. See also internal medicine.

interobserver variation The amount of variation between the results obtained by two or more observers examining the same material.

interphase The interval in the cell cycle between two cell divisions, during which the individual chromosomes cannot be distinguished. Interphase was once thought to be a resting phase, but it is actually the time when DNA is replicated in the cell nucleus.

intersex A group of conditions sometimes referred to as disorders of sexual development (DSDs) in which there is a discrepancy between the appearance of the external genitalia and the type of internal (testes and ovaries) genitalia. The condition was formerly termed hermaphroditism or pseudohermaphroditism. One example of intersex is androgen insensitivity syndrome, in which the…

interstitial Pertaining to being between things, especially between things that are normally closely spaced. The word interstitial is much used in medicine and has specific meaning, depending on the context. For instance, interstitial cystitis is a specific type of inflammation of the bladder wall. Interstitial radiation involves placing radioactive material directly into a tumor. Interstitial…

interstitial radiation See radiation therapy, interstitial.

interstitial-cell-stimulating hormone (ICSH) See luteinizing hormone.

intervening sequence See intron.

interventricular foramen An opening between the lateral and third ventricles in the system of four communicating cavities within the brain that are continuous with the central canal of the spinal cord.

interventricular septum The stout wall that separates the lower chambers (the ventricles) of the heart from one another. A hole in the interventricular septum is termed a ventricular septal defect (VSD).