Abstract

Endocrine cells containing secretin have been identified in the epithelium lining human duodenum by direct and indirect immunoperoxidase techniques using immune sera raised against pur natural secretin. The techniques were applied to sections of carbodiimide-fixed tissue embedded in polyethylene glycol. Some sections, stained by a modified indirect technique, were processed for electron microscopy; secretin-containing granules were present by ultrastructural preservation was too poor to be of value. The potential advantages of a peroxidase technique over fluorescein-coniugated antisera are discussed.