Myocytes are linked by GAP junctions. Development of the epidermis includes proliferation and differentiation. Postnatally, its path is blocked when it constricts and forms the ligamentum arteriosus. The foramen ovale is a shunt that permits blood entering the rt. It is an opening in the interatrial septum.
Cataracts make the lens opaque.
Oldest lens fibers are in the interior of the lens. Oldest keratinocytes are at the surface of the epidermis. The trunococonal septum is the tissue that develops to separate the aortic vs. pulmonary vessels. These are far fetched, but apply what you know about inductive relationships and competence. Umbilical arteries deliver to placenta for same purpose.