All tissue samples a stained before they a looked at under a microscope. Otherwise you can't see the things you need to look for. Do not let this bug you, it means nothing. Different tissues take up different types of stains. What you use on heart tissue is not what you would stain epithelium (mucous membranes of the mouth) with. They are all "special stains"

Brian, stage 4 oral cancer survivor. OCF Founder and Director. The first responsibility of a leader is to define reality. The last is to say thank you. In between, the leader is a servant.