A new method for the construction of tissue microarrrays without recipient paraffin block using custom-built needles

Tissue microarrays are becoming a very useful tool for research and immunohistochemistry and in situ hibridization quality control methods. We developed a new technique that allows to build high density paraffin blocks without using a recipient block for the tissue cores and without using a commercial TMA builder instrument. This technique is based on the construction of TMA needles modifying conventional hypodermic needles and using a computer-generated grid to align the cores on the block mould, that is filled with liquid paraffin. We constructed more than 100 TMA blocks using this metthod, to use as immunohistochemistry and histochemistry positive and negative controls. This technique has the following advantages: is easy to reproduce, affordable to any Pathology laboratory, quick and creates uniform blocks, with up to over 100 cores aligned, adherent and easy to cut, with negligible losses during cutting and immunohistochemistry and in situ hibridization procedures.