Medical Subject Headings
MeSH Vocabulary Changes
In biomedicine and related areas, new concepts are constantly emerging, old concepts are in a state of flux and terminology and usage are modified accordingly. To accommodate these changes, descriptors must be added to, changed or deleted from MeSH with adjustments in the related hierarchies, the Tree Structures.
There are many factors that must be considered in deciding whether to add a MeSH descriptor. An interest in one species of a given genus, may lead to interest in some other species or even all of that genus. Yet, if there is little published about the other species, there is little purpose or advantage in creating a myriad of new descriptors in a vocabulary designed to describe the subject content of published literature.
Before new descriptors are introduced, there is careful consideration of how the concept is currently indexed or cataloged. If the existing descriptors and qualifiers (subheadings) precisely characterize or identify the literature on the subject, there may not be a need for a new descriptor. Both too much change or too little change are to be avoided as MeSH is kept current with changes in biomedical knowledge. In selecting the expressions to be used for a new MeSH descriptor, it is the usual practice to adopt the expression most commonly used by the authors writing in the English language.
Lists are provided of: (a) new descriptors which have been introduced with the latest MeSH version; (b) descriptors which have been deleted, with the subject descriptors that have replaced them; and (c) descriptors previously listed with a different name, following this introduction.