Human tumour tissue microarrays

The diagram above shows the basic method to produce tissue microarrays. An example of a tissue microarray is shown below.

Cores (typically between 0.6 and 1 mm in diameter) are punched out of preserved normal and tumour tissue samples embedded in paraffin blocks. Three cores from each tissue are assembled into an array in a second paraffin block. They are then sectioned with a microtome such that 50 to 100 arrays can be made from the same tissues. Once mounted on a glass slide, these arrays can be immuno-stained for specific expressed tumour markers or subjected to FISH (fluorescence in-situ hybridization) analysis.

full tissue microarray image

In the examples shown, the arrays are first immunoperoxidase stained (yellow-brown) with a specific antibody against a tumour protein expressed in the cells, then counterstained with hematoxylin (blue-red) to reveal the cell nuclei. The tumour tissue can be differentiated from healthy tissue by the preponderance of brown staining.

magnified section of tissue microarray

These images were obtained using a low-cost ($3000) photographic slide scanner (Nikon CoolScan 8000) commonly used to convert photographic transparencies into digital images. The resolution is 10 microns per pixel. Grading of cores by the pathologist requires each core to be imaged at full microscopic resolution.

We are grateful to Vistek Ltd. Toronto for the use of their transparency scanner.

• Contact: Yutaka Amemiya
  Phone: 416-480-6100, ext. 3108 or 3502
  E-mail: yamemiya@sri.utoronto.ca