It just means we've had the misfortune to be in a lab reeking of formalin. You're not missing out on anything meaningful or fun. :-)

And as other folks have said, it's just jargon. The first person said the heart tissue may not have been preserved in a standard way and that could impact the results. I'm pointing out that there are some less-common ways to describe the chemical used to preserve the tissue. We don't know which is right, whether they did something unusual or used very unusual language.