Tissue array construction: Pitfalls, problems, and progress

The tissue array is an economical and efficient tool for translational research. An important factor in constructing tissue arrays is the ability to reliably transfer the pathologic feature of interest from the donor block to the array block. The precision of this transfer is undermined by the distortion of dotted routine sections, which serve as the primary feature-finding device for manual array construction, and by certain tissues such as breast, colon, and skin that prove resistant to being punched. To evaluate and improve this transfer process, with a focus on breast tissue, we investigated a series of waterbath temperatures best suited to minimize microtomy-induced section distortion of breast tissue, and a novel donor block pretreatment before array construction. Our results show that routine sections deviate least from their blocks when transferred to slides in 46°C waterbaths, but also that attention be paid to the crushing effect of the microtome. Core transfer rates are highest when donor blocks are stored at 4°C before punching and when 0.6-mm diameter cores are taken from donor blocks.