Cell types of the endocrine pancreas in the shark Scyliorhinus stellaris as revealed by correlative light and electron microscopy

Cell and Tissue Research
K Kobayashi, S Syed Ali

Abstract

In the pancreas of Scyliorhinus stellaris large islets are usually found around small ducts, the inner surface of which is covered by elongated epithelial cells; thus the endocrine cells are never exposed directly to the lumen of the duct. Sometimes, single islet cells or small groups of endocrine elements are also incorporated into acini. Using correlative light and electron microscopy, eight islet cell types were identified: Only B-cells (type I) display a positive reaction with pseudoisocyanin and aldehyde-fuchsin staining. This cell type contains numerous small secretory granules (diameter 280 nm). Type II- and III-cells possess large granules stainable with orange G and azocarmine and show strong luminescence with dark-field microscopy. Type II-cells have spherical (diameter 700 nm), type III-cells spherical to elongated granules (diameter 450 x 750 nm). Type II-cells are possibly analogous to A-cells, while type III-cells resemble mammalian enterochromaffin cells. Type IV-cells contain granules (diameter 540 nm) of high electron density showing a positive reaction to the Hellman-Hellerström silver impregnation and a negative reaction to Grimelius' silver impregnation; they are most probably analogous to D-cells of other s...Continue Reading

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