This inquiry was, in fact, technically not an email, but rather a Slack message (though isn’t everything email, really?) Nonetheless, it seems like it might be useful to people, so I thought I’d post it here.

Q: @danhoops My local vet tells me he has to euthanise a [lizard] a week. He is happy to chop off the head and we could do MRI + [immunocytochemistry]. What should I give him as preservative?

A: Place the head in formalin/PFA for 24 hours in the fridge, then store in phosphate-buffered saline in the fridge. For samples you want to store long-term, add 0.05% sodium azide to the phosphate-buffered saline to prevent bacteria and fungal growth.

This answer is my opinion, I’d certainly be interested in hearing from anyone with a differing opinion.