Increasing the efficiency of paraffin tissue microarrays by packing the paraffin tissue core biopsies in a honeycomb pattern.

Paraffin tissue microarrays (PTMAs) are blocks of paraffin holding up to 1000 paraffin tissue core biopsies (PTCBs) for high throughput molecular analysis. The number of PTCBs in a PTMA depends on the surface area of the PTMA, the diameter of and the distance between the PTCBs and on their arrangement inside the assembled PTMA. The PTCBs are usually arranged in a rectangular x-y pattern of rows and columns. This design facilitates the construction of a PTMA because the operator simply turns the wheels of an x-y-table for a set, unchanging distance. The evaluation of the stained sections is also relatively easy. However, this rectangular arrangement means wasted space in the PTMA. To reclaim this space, the PTCBs could be arranged in a honeycomblike pattern. For every 8 rows in the conventional rectangular arrangement, 1 additional row of PTCBs can be packed. However, the researcher has to become accustomed to this uncommon arrangement when filling and evaluating the PTMA. Automatic slide readers and specially designed computer programs for the digital evaluation of the PTMAs can be helpful. In summary, the arrangement of PTCBs in a honeycomblike pattern increases the density and number of specimens stored in a PTMA, thereby enhancing its efficiency.