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Study of following, i) T.S. and L.S.of Sycon, T.S. Of Sycon, 1.The section shows cellular grade of organization. It shows outer ectoderm and inner endoderm., 2. The ectoderm is made up of pinacocytes while endoderm is made up of flagellated cells and, choanocytes., 3. The T.S. shows numerous ostia leading to incurrent canal., 4. The incurrent canals open into the radial canals through the prosopyles., 5. Radial canals open into spongocoel by apopyles., 6. The T.S. of sycon shows a large central spongocoel., , T.S. of Sycon