Catholic schools in a Wisconsin diocese will no longer make field trips to a research center that uses embryonic stem cells.
The Wisconsin Institute for Discovery does research using human embryos.
The Vatican opposes that practice.
The Madison diocese issued a letter stating that the research opposes Catholic teaching.
It also said any planned visits to the center should be canceled and schools should pursue other means of meeting educational goals.
The center offers workshops for middle and high school students to work with live human stem cells.