Aminopeptidase reactivity in the digestive tract of adult abalone Haliotis asinina linnaeus

Histologically, the epithelium of the digestive tract is pseudostratified columnar type, which is composed of 3 kinds of cells (i.e., granulated cells, nongranulated cells, and mucus cells). The subsets of these three types of cells vary from region to region. By an enzyme-histochemical method, leucine aminopeptidase reactivity was localized principally within the cytoplasm of granulated cells in the buccal cavity, esophagus, esophageal pouch, hepatopancreas, and the third intestinal region, which implies that these sites are responsible for the synthesis and secretion of this peptidase for the digestion of proteinaceous nutrients.