Setup of the cranial slice imaging system. (A) Schematic showing steps to making a cranial slice. A slice of a 0.5-0.8 mm thickness is excised at the dotted lines through the trigeminal region of the embryo shown by the cartoon which is then embedded in a collagen matrix on the cover glass-bottom dish. A representative slice (right) showing high cellular resolution when tissue is in focus, where ectoderm (ecto), mesenchyme (mes), neural tube (nt), notochord (n), and lens (le) are clearly delineated. White arrows show direction of placodal cell migration into mesenchyme. (B) DeltaVision Core microscope workstation with a built-in incubator chamber (left) and magnified view of the cover glass-bottom dish with several collagen cultures (red arrow) on the microscope stage with a carbon dioxide/air mix input source.