Placenta and cancer research. Fluorescent light micrograph of placenta tissue, specifically the cells that line the villi of the placenta. The yellow colour highlights the presence of Vista protein. Vista is a molecule that regulates T lymphocytes (a type of white blood cell) and plays an important role in the immune system. It is being studied to help develop immunotherapy treatments for cancer. Red represents CD8 protein, while blue represents the cell nuclei. The presence of the Vista molecule in placental cells indicates that they can be used as control tissue for immunofluorescent staining assays of Vista in cancer research studies.