Echinodermata, Hemichordata and Xenoturbellida form the clade Ambulacraria. The present phylum Priapulida also has a deuterostomic development, despite being otherwise placed within the protostomes. In both deuterostomes and protostomes, a zygote first develops into a hollow ball of cells, called a blastula.In deuterostomes, the early divisions occur parallel or perpendicular to the polar axis. This is called radial cleavage, and also occurs in certain protostomes, such as the lophophorates.chinodermata, Hemichordata and Xenoturbellida form the clade Ambulacraria. The present phylum Priapulida also has a deuterostomic development, despite being otherwise placed within the protostomes. In both deuterostomes and protostomes, a zygote first develops into a hollow ball of cells, called a blastula.
In this test you drink some barium liquid. The barium liquid is often fruit-flavoured so it is pleasant to drink. You stand in front of an X-ray machine whilst X-ray pictures are taken as you swallow. This test aims to look for problems in the gullet (oesophagus).
Barium is a metal, but has no significant uses as such. A significant medical use of barium is to enhance x-ray images of the intestinal tract. Barium has a high atomic number and absorbs x-rays strongly. A thin paste of barium sulfate, BaSO 4, and water is is swallowed to coat the alimentary canal.This gives greater definition and contrast to the x-ray images of the tract.The low solubility of barium sulfate minimizes the toxic effects which might occur with other barium compounds.The mineral form of barium sulfate is called barite.his gives greater definition and contrast to the x-ray images of the tract. The low solubility of barium sulfate minimizes the toxic effects which might occur with other barium compounds. The mineral form of barium sulfate is called barite.