Medical Subject Headings
MeSH Vocabulary Changes
In biomedicine and related areas, new concepts are constantlyemerging, old concepts are in a state of flux and terminology andusage are modified accordingly. To accommodate these changes,descriptors must be added to, changed or deleted from MeSH withadjustments in the related hierarchies, the Tree Structures.
There are many factors that must be considered in decidingwhether to add a MeSH descriptor. An interest in one species of agiven genus, may lead to interest in some other species or evenall of that genus. Yet, if there is little published about theother species, there is little purpose or advantage in creating amyriad of new descriptors in a vocabulary designed to describethe subject content of published literature.
Before new descriptors are introduced, there is carefulconsideration of how the concept is currently indexed orcataloged. If the existing descriptors and qualifiers(subheadings) precisely characterize or identify the literatureon the subject, there may not be a need for a new descriptor.Both too much change or too little change are to be avoided asMeSH is kept current with changes in biomedical knowledge. Inselecting the expressions to be used for a new MeSH descriptor,it is the usual practice to adopt the expression most commonlyused by the authors writing in the English language.
Lists are provided of: (a) new descriptors which have beenintroduced with 2009 MeSH; (b) descriptors which have beendeleted, with the subject descriptors that have replaced them;and (c) descriptors previously listed with a different name,following this introduction.