Dictionary

tympanic membrane The eardrum, a thin membrane that serves as a partition between the external ear and the middle ear and transmits the motion of sound waves to the chain of bones in the middle ear.

twin One of two children produced in the same pregnancy. Twins can develop from one ovum (egg) or from two ova (eggs). Twins who develop from a single ovum are called monozygotic or identical twins. They have identical genomes. Twins who develop from two ova that are fertilized at the same time are called dizygotic…

TVS Transvaginal ultrasound.

Turner syndrome The most common sex chromosome disorder in females, characterized by short stature, webbed neck, broad shield-like chest, widespaced nipples, increased carrying angle at the elbow (cubitus valgus), short fourth finger, and malformations of the heart and aorta. The intelligence of those with Turner syndrome is usually within the normal range. Girls with Turner…

Turcot syndrome A genetic disease characterized by polyps in the colon (large intestine) in addition to tumors in the brain. The polyps in the colon tend to become malignant. The brain tumors are also malignant. Skin abnormalities can also occur. Turcot syndrome is inherited in an autosomal recessive manner and can result from mutations in…

turbinate A bone in the nose that is situated along the side wall of the nose and is covered by mucous membrane.

TUR Transurethral resection.

tunnel Any passageway in the body that traverses solid tissue and is completely enclosed except for the ends, which are open and permit entrance to and exit from the tunnel. An example of a tunnel is the carpal tunnel.

tunica albuginea The whitish membrane within the penis that surrounds the spongy chambers (corpora cavernosa). The tunica albuginea helps to trap the blood in the corpora cavernosa, thereby sustaining erection of the penis.

tumor suppressor gene A protective gene that normally limits the growth of tumors. When a tumor suppressor gene is mutated (altered), it may fail to keep a cancer from growing. BRCA1, an example of a tumor suppressor gene, was the first breast cancer gene to be identified; mutated forms of this gene are responsible for…

tumor registry Recorded information about the status of patients with tumors. Although a registry was originally the place where information was collected (in registers), the word registry has also come to mean the collection itself. A tumor registry is organized so that the data can be analyzed. For example, analysis of data in a tumor…

tumor necrosis factor One of multiple proteins capable of inducing necrosis (death) of tumor cells that possess a wide range of proinflammatory actions. Abbreviated TNF. TNF is a multifunctional cytokine with effects on lipid metabolism, coagulation, insulin resistance, and the function of endothelial cells lining blood vessels. Drugs that block the action of TNF have…