in vivo In the living organism. For example, an experiment that is done in vivo is done in the body of a living organism as opposed to in a laboratory method that does not use the living organism as the host of the test. In vivo is the opposite of in vitro.
in vitro fertilization A laboratory procedure in which sperm are put in a special dish with unfertilized eggs to achieve fertilization. The embryos that result can be transferred into the uterus or frozen (cryopreserved) for future use. Abbreviated IVF.
in vitro In glass, as in a test tube. An in vitro test is one that is done in glass or plastic vessels in the laboratory. In vitro is the opposite of in vivo.
in situ hybridization The use of a DNA or RNA probe to detect complementary genetic material in cells or tissue. In situ hybridization involves hybridizing a labeled nucleic acid to suitably prepared cells or tissues on microscope slides to allow visualization in situ (in the normal location).
in situ, carcinoma See carcinoma in situ.
in situ In the normal location. An in situ tumor is one that is confined to its site of origin and has not invaded neighboring tissue or gone elsewhere in the body. For example, squamous cell carcinoma in situ is an early stage of skin cancer.
in. Abbreviation for inch.
imprinting, psychological A remarkable phenomenon that occurs in animals, and theoretically in humans, in the first hours of life. The newborn creature bonds to the type of animals it meets at birth and begins to pattern its behavior after them. In humans, this is often called bonding, and it usually refers to the relationship between…
impotence See erectile dysfunction.
implantable pacemaker See pacemaker, internal.
implantable cardiac defibrillator See cardiac defibrillator, implantable.
implant, cochlear See cochlear implant.