Progressive processing of ingested water in the gut of sea-water teleosts

The European eel's oesophagus, stomach and anterior and posterior intestine were perfused separately, in vivo. The oesophagus and anterior intestine play a major part in processing of ingested water. Serosal potential differences to mucosal measured in vivo were positive in all gut segments. The C1- concentrations of luminal contents in different parts of the gut were measured in nine species of sea-water teleosts. The progressive decrease in C1- concentration resulted from local processing of the ingested sea water, and the beginnings of the oesophagus and of the intestine were the major processing sites.