I thought he was a biochemist and taught at a med school. Wikipedia says he started writing scifi at 11, and I doubt even he was eligible for med school at that age.
Wikipedia says that he applied to med school, was rejected, went to grad school in chemistry at Columbia (partially before and partially after World War II), and then after getting his PhD he taught at the Boston University School of Medicine. So he taught at a med school without attending a med school.