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An exogenous contrast agent, in medical imaging for example, is a liquid injected into the patient intravenously that enhances visibility of a pathology, such as a tumor.An exogenous factor is any material that is present and active in an individual organism or living cell but that originated outside that organism, as opposed to an endogenous factor.
For example, endogenous substances, and endogenous processes are those that originate within a living system (e.g. an organism or a cell). For instance, estradiol is an endogenous estrogen hormone produced within the body, whereas ethinylestradiol is an exogenous synthetic estrogen, commonly used in birth control pills.
His theory proposed geomorphology is based on endogenous and exogenous processes. [18] Penck's theory, while ultimately being ignored, returned to denudation and uplift occurring simultaneously and relying on continental mobility, even though Penck rejected continental drift. The Davisian and Penckian models were heavily debated for a few ...
Transfection is the process of introducing exogenous DNA into eukaryotic cells. [12] It is a more specific term for animal cells, as the process of carcinogenesis in these cells is also included in the definition of transformation. Typically, transfection describes the changes in a cell's genome due to the introduction of foreign DNA. [4]
The exogenous pathway is utilized by specialized antigen-presenting cells to present peptides derived from proteins that the cell has endocytosed. The peptides are presented on MHC class II molecules. Proteins are endocytosed and degraded by acid-dependent proteases in endosomes; this process takes about an hour. [1]
In an economic model, an exogenous variable is one whose measure is determined outside the model and is imposed on the model, and an exogenous change is a change in an exogenous variable. [1]: p. 8 [2]: p. 202 [3]: p. 8 In contrast, an endogenous variable is a variable whose measure is determined by the model. An endogenous change is a change ...
Exogenous bacteria are microorganisms introduced to closed biological systems from the external world. [citation needed] They exist in aquatic and terrestrial environments, as well as the atmosphere. Microorganisms in the external environment have existed on Earth for 3.5 billion years. [1] Exogenous bacteria can be either benign or pathogenic.
Surficial processes are the physical and chemical phenomena which cause concentration of ore material within the regolith, generally by the action of the environment. This includes placer deposits, laterite deposits, and residual or eluvial deposits. Superficial deposits processes of ore formation include; Erosion of non-ore material.