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Be careful when storing Histology blocks

Many times users of histology service labs bring back blocks that have been sectioned before and ask for additional sections. This is usually a simple thing for the lab to do if the blocks have been stored properly.

Occasionally the lab is given blocks that were stored near a window, or in a car, or next to the exhaust fan of an instrument that tends to run hot. When the blocks get too warm, the wax begins to soften and the smooth surface of the block can become deformed. To recut the sample, the block often needs to be re-embedded (melted down and re-oriented). If the piece of tissue in the block is small or thin, some of the valuable tissue may be lost while trying to section into the sample. Please store your blocks with care.

NOTE: The paraffin used in the histology labs often has a melting point of 55-57°C (131-135°F).