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 swallow is a dedicated test of the pharynx, oesophagus, and proximal stomach, and may be performed as a single or double contrast study.arium swallow is a dedicated test of the pharynx, oesophagus, and proximal stomach, and may be performed as a single or double contrast study.