In situ
In situ is a
Latin phrase meaning
in place. It is used in many different contexts.
In archaeology,
in situ refers to an artifact that has not been moved from its originial place of deposition. An artifact being
in situ is critical to the interpretation of that artifact and, consequently, to the culture which formed it. Once an artifact's provenance has been recorded, the artifact can then be moved for conservation, further interpretation and display. An artifact that is not discovered
in situ is considered out of context and will not provide an accurate picture of the associated culture. However, the out of context artifact can provide scientists with an example of types and locations of
in situ artifacts yet to be discovered.
In
biology,
in situ means to examine the phenomenon exactly in place where it occurs (without removing it in some special medium etc.). Usually means something intermediate between
in vivo and
in vitro. For example, examining a cell within a whole
organ intact and under
perfusion may mean
in situ investigation. This is not obviously in vivo experimenting because an animal is sacrificed, but it is not the same as working with the cell alone (which may be a perfect case of an in vitro experiment).
In
oncology, for a
carcinoma which is a cancer of an
epithelium,
in situ means that malignant cells are present in the epithelium but has not invaded beyond the
basal lamina into deeper tissues.
In
genetics,
in situ can also mean
in the chromosome. For example,
FISH can be done with chromosomes in cells or in a karyotype, such as with
spectral karyotyping. In each case, we are observing the target sequence(s) where they are in the chromosome.
In chemistry, there are numerous unstable molecules which must be synthesized
in situ for use in various processes. Examples include the
Corey-Chaykovsky reagent and
adrenochrome.
In
physical geography and the
Earth sciences,
in situ typically describes natural material or processes prior to transport. For example,
in situ is used in relation to the distinction between
weathering and
erosion, the difference being that erosion requires a transport medium (such as
wind,
ice, or
water), whereas weathering occurs
in situ.
Geochemical processes are also often described as occurring to material
in situ.
In the
atmospheric sciences, in situ refers to measurements obtained through direct contact with the respective subject, such as a
radiosonde measuring a parcel of air or an
anemometer measuring wind, as opposed to
remote sensing such as weather radar or satellites.
In situ can refer to where a clean up or
remediation of a
polluted site is performed using and simulating the natural processes in the
soil, contrary to
ex situ where contaminated soil is
excavated and cleaned elsewhere, off site.
In
literature in situ is used to describe a condition. The
Rosetta Stone, for example, was originally erected in a courtyard, for public viewing. Most pictures of the famous stone are not
"in-situ" pictures of it erected, as it would have been originally. The stone was uncovered as part of building material, within a wall. Its
in situ condition today is that it is erected, vertically, on public display at the
British Museum.
In
linguistics, specifically
syntax, an element may be said to be
in situ if it is pronounced in the position where it is interpreted. For example,
questions in languages such as
Chinese have
in-situ wh-elements, with structures comprable to "John bought what?" while
English wh-elements are not
in-situ: "What did John buy?"
In
legal context,
in situ is often used for its literal meaning. For example, in
Hong Kong,
in situ land exchange involves the Government exchanges the original or expired
lease of a piece of land with a new
grant or re-grant with the same piece of land or a portion of that.
carcinoma in situex vivoin silicoin uteroin vitroin vivo*
List of Latin phrases
