IDENTIFICATION OF 2 SOMATOSTATIN-IMMUNOREACTIVE CELL-TYPES IN THE PRINCIPAL ISLET OF SPARUS-AURATUS L (TELEOSTEI) BY IMMUNOGOLD STAINING

Two types of somatostatin (SST 14)-immunoreactive cells are identified by immunogold staining in the Lowicryl-embedded principal islet of Sparus auratus: D1 cells, having large moderate to low electron dense granules, located between A cells in the islet periphery and D2 cells, containing smaller electron-dense granule s,.present between B cells in the central region of the islet. Although SST 28-like immunoreactivity was not observed in D cells of S. auratus, the presence of SST 14 and a SST 22-,25-, or 28-like sequence in D2 and D1 cells, respectively, is discussed. A third SST 14-immunoreactive cell, found in the islet periphery, showed immunoreactive D1- and unreactive A-like granules. This cell type, which has a pyknotic-like nucleus and a dark appearance in osmicated Epon-embedded tissue, is supposed to be the product of fusion of D1 and A cells. © 1990.