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A primary advantage of using ex vivo tissues is the ability to perform tests or measurements that would otherwise not be possible or ethical in living subjects. Tissues may be removed in many ways, including in part, as whole organs, or as larger organ systems. [citation needed] Examples of ex vivo specimen use include: [citation needed]
Typically, most candidate drugs that are effective in vitro prove to be ineffective in vivo because of issues associated with delivery of the drug to the affected tissues, toxicity towards essential parts of the organism that were not represented in the initial in vitro studies, or other issues. [33]
In microbiology, in vivo is often used to refer to experimentation done in a whole organism, rather than in live isolated cells, for example, cultured cells derived from biopsies. In this situation, the more specific term is ex vivo. Once cells are disrupted and individual parts are tested or analyzed, this is known as in vitro. [citation needed]
The problem of transposing in vitro results is particularly acute in areas such as toxicology where animal experiments are being phased out and are increasingly being replaced by alternative tests. Results obtained from in vitro experiments cannot often be directly applied to predict biological responses of organisms to chemical exposure in vivo.
Tissue culture is an important tool for the study of the biology of cells from multicellular organisms. It provides an in vitro model of the tissue in a well defined environment which can be easily manipulated and analysed. In animal tissue culture, cells may be grown as two-dimensional monolayers (conventional culture) or within fibrous ...
In vitro was among the first attempts to qualitatively and quantitatively analyze natural occurrences in the lab. Eventually, the limitation of in vitro experimentation was that they were not conducted in natural environments. To compensate for this problem, in vivo experimentation allowed testing to occur in the original organism or environment.
A bioassay is an analytical method to determine the potency or effect of a substance by its effect on living animals or plants (in vivo), or on living cells or tissues (in vitro). [1] [2] A bioassay can be either quantal or quantitative, direct or indirect. [3] If the measured response is binary, the assay is quantal; if not, it is quantitative ...
These techniques can be performed either in vivo, ex vivo, or in vitro. [3] Ex vivo techniques enable a more accurate count of the T cells in a graft and also has the option to 'addback' a set number of T cells if necessary. Currently, ex vivo techniques most commonly employ positive or negative selection methods using immunomagnetic separation.