Frequently Asked Questions

General questions regarding tissue arrays :

What about tumor heterogeneity ? How many cores per case are required ?

How many specimens can be included per array block ?

How long does it take to make a tissue array ?

How do you cut sections from a tissue array block ?

How many sections can be cut from a tissue array block ?

How can you make frozen tissue arrays ?

Questions about the Beecher manual arrayer:

How to align punches in the manual arrayer ?

General questions:

What about tumor heterogeneity and tissue arrays ? How many punches do you need to get a good representation ?

Depends on tissue type and the purpose of the study. As a rule of the thumb, making tissue arrays from normal breast epithelium, normal kidney and cancers with high degree of regional heterogeneity probably require 2-4 punches per tissue whereas most cancers are well represented with 1-2 punches. See Camp et al, and Torhorst et al, for technology validation papers discussing the use of tissue arrays in evaluating prognostic markers.

How many specimens can you include per array block ?

Number of specimens per array depends on the size of the punches and the desired array density. Using 0.6 mm punches you can construct tissue arrays with 500 or more specimens per block using regular tissue cassettes. Using 2 mm punches allows construction of tissue arrays with about 50-100 specimens.

How long does it take to make tissue arrays ?

Making tissue arrays should be considered as a project that involves many steps. Array construction itself is relatively fast as compared to the other, necessary preparatory steps that include marking of the representative tissue areas for punching. It is realistic to reserve a couple of weeks for completing tissue array construction project for an array consisting of 400 specimens. Because setting up an arraying project takes a considerable amount of time, it often makes sense to construct multiple replicas of the array blocks simultaneously. Making multiple replicate tissue array blocks is faster and more convenient with the automated arrayer than with the manual arrayer. See Arrayer comparison table for estimated core transfer rates for the automated and manual instruments.

How do you cut sections from the array block ?

Some users prefer to cut sections using regular microtome sectioning techniques, some prefer to use adhesive-coated slides from Instrumedics. The advantage of using coated slides is that even beginners can make good sections with the system and you have precise control over the orientation of the tissue array sections on the microscope slides. If you decide to apply conventional sectioning techniques, briefly heating the block at 35-37 degrees C for about 20-30 minutes (and letting the block to cool back to room temperature) before sectioning improves the section quality.

How many sections can you cut from typical tissue arrays ?

Depending on the height of the original donor tissue blocks you can cut 100-300 sections from tissue arrays. 150 sections is a reasonable expectation for a typical tissue array.

Can you make frozen tissue arrays with Beecher's instruments ?

It is possible to make small frozen tissue arrays with the manual instrument. See Fejzo et al for description. However, this approach is relatively difficult and keeping the tissue array quality high is challenging. Beecher is currently working on a prototype frozen tissue arrayer device.This instrument is not yet available for sale, but you can contact us regarding custom arraying.

Questions about the manual arrayer:

How to align punches in the manual arrayer ?

First, to verify punch alignment, place a blank paraffin block in the block holder and put this complex in position on the arrayer as if it were a recipient block. Press the smaller punch down until it leaves a mark in the paraffin surface. Move the turret to switch the larger sampling punch in position, and again make a mark on the paraffin surface. Adjustment is needed if the marks are not coincidental. Punch holes that appear one in front of the other need front to back adjustment; holes to the side of each other require left-to-right alignment. The blue arrow points to the left-to-right setscrews, the orange arrow indicates the location of front-to-back setscrews.