AN AUTORADIOGRAPHIC AND HISTOCHEMICAL INVESTIGATION OF THE GUT MUCOPOLYSACCHARIDES OF THE PURPLE SEA URCHIN (STRONGYLOCENTROTUS PURPURATUS)

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Abstract
The distribution and characteristics of the mucopolysaccharides of the gut of the purple sea urchin were studied by staining with PAS, alcian blue and azure A. The incorporation of S35 -sulfate into the mucopolysaccharides was determined by autoradiography. The connective tissue-muscle layer between the inner epithelium and the coelomic epithelium contains a neutral mucopolysaccharide. In the inner epithelium, mucopolysaccharides are found in unicellular glands located in all gut regions preceding the junction of the esophagus and stomach; such glands never occur in gut regions following this junction. Many, and perhaps all, of the mucopolysaccharides of these glands are acidic. Of these acid mucopolysaccharides, some are sulfated and some are not. In some types of gland cells of urchins killed one hour after injection of S35-sulfate, autoradiograms show an incorporation of the radioisotope in the middle third of the cells, possibly in the Golgi apparatus. In urchins killed 18 hours after injection of S35-sulfate, autoradiograms reveal a migration of the radioisotope to the border of the gland cells adjacent to the gut lumen. In some cases, the initially -sulfated material is refractory to specific histochemical tests for sulfated acid mucopolysaccharides, perhaps because the mucopolysaccharides are masked at synthesis by combination with protein.