Special pathology services
Tissue microarray construction
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TISSUE MICROARRAY (TMA)
The TMA blocks are produced by relocating small cylindrical tissue cores from individual donor blocks and placing them in a recipient “Master” block with defined array coordinates. Arrays are typically constructed from formalin-fixed paraffin embedded (FFPE) tissues by the removal of 0.6-2mm diameter tissue core from donor blocks. A morphologically representative area of interest from the donor block is identified under the microscope by a pathologist using a stained Hematoxylin and Eosin (H&E) section of a glass slide as a guide. Using a precise spacing pattern on an Automated or Manual TMA instrument (Beecher Instruments, WI, USA) 50-500 cores could be transferred to a recipient block in a grid like fashion, retaining a link to the original block and its pathology. Up to 200 consecutive sections can be cut from each “Master” TMA block and used in a large variety of studies including DNA by FISH/CISH, RNA by mRNA ISH, and protein by immunohistochemistry (IHC).
TMA construction steps:
- Selection of cases for TMA
- Review of original H&E slides by a pathologist
- Defining morphologically representative areas and circling them
- Selection of matching FFPE donor blocks
- Preparation of recipient block using low melting wax
- Designing the array
- Construction of TMA using either Automated (ATA-27) or manual Arrayer (MT-1)
- Sectioning of TMA block
- H&E staining of TMA section to confirm morphology
- Producing datasheet with TMA grid and morphological details
