Protostomia (from Greek meaning mouth first) are a clade of animals. Together with the deuterostomes and other phyla, they make up the Bilateria, mostly comprising animals with bilateral symmetry and three germ layers.The major distinctions between deuterostomes and protostomes are found in embryonic development.In animals at least as complex as earthworms, the embryo forms a dent on one side, the blastopore, which deepens to become the archenteron, the first phase in the growth of the gut.ogether with the deuterostomes and other phyla, they make up the Bilateria, mostly comprising animals with bilateral symmetry and three germ layers. The major distinctions between deuterostomes and protostomes are found in embryonic development.
A barium enema, or lower gastrointestinal (GI) examination, is an X-ray examination of the large intestine (colon and rectum). The test is used to help diagnose diseases and other problems that affect the large intestine. To make the intestine visible on an X-ray picture, the colon is filled with a contrast material containing barium. This is done by pouring the contrast material through a tube inserted into the anus.
A barium swallow is an X-ray test is for investigating complaints related to the esophagus. A barium meal test evaluates the stomach and upper small intestine.