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

¹ Hopkins Marine Station of Stanford University, Pacific Grove, California

1. A neutral mucopolysaccharide, probably associated with a protein, occurs in the connective tissue-muscle layer of all gut regions of the purple sea urchin.

2. In the inner epithelium, mucopohysaccharides 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.

3. Many, and perhaps all, of the mucopohysaccharides of these unicellular glands arc acidic. Of these acid mucopoiysaccharides, some are sulfated and others arc not.

4. Autoradiograms show that some gland cells which contain acidic sulfated mucopolysaccharides first incorporate S³⁵-sulfate in the middle third of the cell. In some cases, the initially-sulfated material is refractory to specific histochemical tests for sulfated acid mucopolysaccharides, perhaps because the mucopolysaccharides are masked by combination with protein.

5. Autoradiograms show a migration of sulfated material from the middle third to the luminal portion of some gland cells. In cases where the sulfated material was masked when synthesized in the middle third of the cell, it becomes unmasked when it reaches the luminal part of the cell.