pl. media
1. An agent through which an effect is obtained.
2. A substance used for the cultivation of microorganisms or cellular tissue.
SEE: culture medium
3. A substance through which impulses are transmitted.

Amies transport medium

SEE: Amies transport medium

BG medium

Bordet-Gengou medium.

clearing medium

A substance that renders histological specimens transparent.

contrast medium

In radiology, a substance used to fill hollow organs or blood vessels to highlight their internal structure or distinguish them from neighboring anatomical features. The substance can be radiopaque and positive (such as barium sulfate, tri-iodinated media) or radiolucent and negative (such as air). Barium sulfate is a commonly used contrast agent for the gastrointestinal tract; it may be swallowed (for upper GI studies) or given as an enema (to visualize the colon).
SYN: SEE: radiocontrast

culture medium

A substance on which microorganisms may grow. Those most commonly used are broths, gelatin, and agar, all of which contain the same basic ingredients.

defined medium

In bacteriology, a culture medium in which the composition is accurately defined and carefully controlled. One of its uses is to investigate the influence of altering ingredients on bacterial cell growth characteristics.

dispersion medium

A liquid in which a colloid is dispersed.

high-osmolarity contrast medium

ABBR: HOCM A water-soluble contrast medium with high osmolarity. HOCMs increase the probability of an adverse reaction and are generally ionic.

Lowenstein-Jensen medium

SEE: Lowenstein-Jensen medium

low-osmolarity contrast medium

ABBR: LOCM A water-soluble contrast medium with low osmolarity. LOCMs produce fewer undesired effects after intravascular administration than do high-osmolarity contrast media. They are generally nonionic, with the exception of Hexabrix (an ionic dimer).

Luria-Bertani medium

SEE: Luria-Bertani medium

nonionic contrast medium

A water-soluble contrast medium whose molecules do not dissociate into cations and anions in solution. Nonionic contrast media tend to have low osmolarity. They decrease the risk of adverse reactions but are costly.

nutrient medium

A fortified culture medium with added nutrient materials.

radiolucent medium

A substance injected into an anatomical structure to decrease the density, producing a dark area on the radiograph.

radiopaque medium

A substance injected into a cavity or region or passed through the gastrointestinal tract to increase x-ray absorption, producing an image with enhanced contrast between solid and hollow structures.

refracting medium

Any of the fluids and transparent tissues of the eye that refract light rays passing through them toward the retina: the cornea, aqueous humor, lens, and vitreous humor.

Roswell Park Memorial Institute medium

A phosphate-rich growth medium used to sustain cells (such as lymphocytes and macrophages or cancer cells) in laboratory culture.

selective medium

A culture medium that inhibits the growth of some microorganisms so that organisms of greater interest can be isolated.

separating medium

In dentistry, a substance applied to the surface of an impression or mold to prevent interaction of the materials and to facilitate their separation after casting.

Thayer-Martin medium

SEE: Thayer-Martin medium

transport medium

A nutrient solution used to maintain the freshness or viability of patient specimens as they are being carried to the laboratory for culture.

tri-iodinated contrast medium

A derivative of tri-iodobenzoic acid that is the base for water-soluble contrast media. It contains three atoms of iodine per molecule.

viral transport medium

ABBR: VTM A nutrient substance (usually a buffered liquid) used to carry and maintain the viability of specimens to a microbiology laboratory for identification and analysis of disease-producing viruses.