A long time ago, I (a cohen) was considering med school. I contacted Rav Aharon Soleveitchik to ask what I could do about anatomy lab. He told me that I could be in the cadaver lab but not touch or move anything. He told me because of or Rov Goyim there was no worry of tumat ohel.
It could be that in some areas, like NYC metro, there are so many Jews that you cannot assume that there is not any tumat ohel (cadavers from Jews). I was not living in the NYC area at the time of that psak, so don’t know what he would have said in that case. Just raising the question/issue.