Abstract
Endocrine cells were observed in the digestive tracts of the medaka, Oryzias latipes, by light and electron microscopy.These cells showed positive staining with lead haematoxylin.Tests for argentaffin and chromaffin reaction were negative.Endocrine cells are always found straggled in the mucous epithelium.They have many secretory granules in the cytoplasm.Five types of endocrine cells (I, II, III, IV, and V) are identified by the morphological characteristics of their secretory granules.In every endocrine cell type, the basal part directly faces the basement membrane of the epithelium.The apical part of the type IV and V cells reaches the digestive lumen, and microvilli are recognized in the apical cytoplasm.The cell membrane of the base and side often appears hollow and Ω-shaped.It is suggested that secretory granules may be released into the connective tissue or intercellular space by the emiocytosis.
