I didn't let anything in my classroom that was embalmed. The chemicals used are toxic, and students should never be exposed to them. I also only used things for dissection that could be bought in my local meat departments, such as chicken wings, soup bones, and chicken hearts.
However, I found that the icky factor was fascinating to deal with. Some kids had no problem, and others that did either realized what they were eating was what their parents cooked, and they ate or decided to become vegans (at least temporarily). I never insisted they had to do the dissections if they were squeamish. They could even ask to be elsewhere when it happened. I had arrangements with the other teachers and librarian.