Electron microscopic immunohistochemical investigation of chromogranin A in endocrine cells in human oxyntic gastric mucosa

Human oxyntic gastric mucosa harbours 6 types of endocrine cells: enterochromaffin-like (ECL) cells, enterochromaffin (EC) cells, somatostatin (D) cells, and cells with an unknown secretory product (P cells, D1 cells and X (A-like) cells). In the present study, intracellular localization and granular content of chromogranin A (CGA) in these cells have been investigated by electron microscopic immunohistochemistry. The content of CGA in granules of the various types of endocrine cells was evaluated and compared with the content of serotonin and somatostatin in EC cells and D cells, respectively. ECL cells, EC cells, P cells, D1 cells and X cells contained CGA in their granules, whereas D cells did not. CGA granular content in ECL cells, P cells, D1 cells and X cells was 3.39 +/- 0.17, 3.41 +/- 0.21, 3.58 +/- 0.18, and 3.55 +/- 0.09, respectively. In ECL cells, CGA was also found in a nongranular form. The CGA content in EC cells (2.95 +/- 0.21) was not significantly different from the serotonin content (2.82 +/- 0.11; p > 0.05) which is in line with the basic significance of CGA as potential amine storage and release protein. The somatostatin content in D cells was 3.30 +/- 0.15. Our study has established high content of CGA in granules of all types of endocrine cells in human oxyntic gastric mucosa except in D cells.