National Cancer Institute U.S. National Institutes of Health
Cancer Diagnosis Program (CDP)
CDP Tissue Microarrays

TMA Definitions

Tissue Microarray
A tissue microarray is a group of cores taken from donor blocks of paraffin embedded tissue, which are selected based on specific case criteria and systematically arrayed in new paraffin blocks to construct powerful research tools for the simultaneous evaluation of markers in many tissue specimens, and to permit meaningful comparisons between the donor specimens. An array may consist of one or more case sets.

An example of how a TMA is produced.

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TMA Case Set
A case set is a non-overlapping subset of the donor tissue blocks selected for the construction of a tissue microarray. For example, to construct the Progression TMA the CDP assembled a collection of 679 breast tissue specimens, which was divided into six unique case sets, Case Sets 3-8, each representing between 112-115 breast tissue specimens. A complete array consists of three case sets.
TMA Block
A TMA block is a paraffin block in which tissue cores are embedded in a systematic array. TMA sections are cut from the TMA blocks in cross-section, and mounted on slides (one section per slide). The CDP does not make entire TMA blocks available to applicants.
TMA Section
A TMA section is a thin cross-section cut from a TMA block, and mounted on a slide. CDP TMA sections are mounted one to a slide. For example, an investigator who is approved to receive a 10-section set of the breast cancer Stage I Prognostic TMA will receive a total of 10 slides
TMA Array Set
A TMA array set is a collection of TMA sections representing the minimum number of case sets recommended to complete an experiment.