Ultrastructural aspects of the neuroendocrine complex in the stomach in patients with either pernicious anemia or the Zollinger-Ellison syndrome.

: The neuroendocrine complex of the gastrointestinal tract is defined as the presence of neuroendocrine cells in the lamina propria and in direct contact with nerve fibres of Meissner's plexus. The entire complex is separated from the interstitium by a basement membrane. To date, only a few studies have been published on the neuroendocrine complex. In this prospective electron microscopic study, we investigated the neuroendocrine complex of the stomach in 21 patients with pernicious anemia, and in eight patients with the Zollinger-Ellison syndrome. For each patient, six step biopsies obtained from the stomach at endoscopy were investigated. 16 out of the 21 patients with pernicious anemia, and four of the eight patients with the Zollinger-Ellison syndrome were found to have neuroendocrine complexes in the gastric mucosa. In patients with pernicious anemia who had neuroendocrine complexes more neuroendocrine complex-positive biopsies were found, on average, per patient, and more and larger neuroendocrine complexes, on average, per biopsy, than was the case in patients with the Zollinger-Ellison syndrome. These results show that in the gastric mucosa of patients with pernicious anemia, more marked proliferation of neuroendocrine complexes occur than in patients with Zollinger-Ellison syndrome.