Operation (game) around the United States. It consists of an "operating table", lithographed with a comic likeness of a patient (nicknamed "Cavity Sam") with a large red lightbulb for his nose. This could be a reference to classic cartoons, where ill characters' noses turn red. In the surface are a number of openings, which reveal cavities filled with fictional and humorously named ailments made of plastic. The general gameplay requires players to remove these plastic ailments with a pair of tweezers without touching the edge of the cavity opening. "Operation" includes two sets of cards: The "Specialist" cards are dealt out evenly
Body cavity tube rolls up and closes ventrally to create a “tube on top of a tube.” The mesoderm, which is another layer of the trilaminar germ disc, holds the tubes together and the lateral plate mesoderm, the middle layer of the germ disc, splits to form a visceral layer associated with the gut and a parietal layer, which along with the overlying ectoderm, forms the lateral body wall. The space between the visceral and parietal layers of lateral plate mesoderm is the primitive body cavity. When the lateral body wall folds, it moves ventrally and fuses at the midline. The body