In common parlance, a stem is any elongated, usually narrow, extension or supporting structure of an object. Examples are the stem of a smoking pipe, stem of a cut flower, stem of a wine glass, etc. Uses of the term specific to certain fields are as follow:
In music, a stem is part of the annotation used to write musical notes.
In rock climbing, a stem is a move that involves two widely spaced holds.
In linguistics, a stem is the base part of the word including derivational affixes but not inflectional morphemes, i. e. the part of the word that remains unchanged through inflection.
In typography, a stem is the upright element of a letter or character. The letter 'i' has one stem, 'n' has two stems, and 'm' has three.
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Research with embryonic stem cells derived from humans is controversial because, in order to start a stem cell 'line' or lineage, it requires the destruction of a blastocyst (an embryo that has not yet grown beyond 150 cells), which some people believe to be human beings.
Stem cells which derived from the inner mass cells of a blastocyst (an early embryo) have pluripotent properties—they are able to grow into any of the 200 cell types in the body.
Embryonic stem cell researchers are currently attempting to grow the cells beyond the first stages of cell development, to overcome difficulties in host rejection of implanted stem cells, and to control the multiplying of implanted embryonic stem cells, which otherwise multiply uncontrollably, producing cancer.
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